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PPMS Resistivity Manual

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1. e UT g Unscrew the two rack mount screws that attach the Model 6000 to the console cabinet rack Carefully slide the Model 6000 forward and out of the console approximately 2 inches 5 13 cm Make certain that you support the full weight of the Model 6000 Remove the two front top cover screws see B in figure A 1 Carefully slide the Model 6000 back into the console cabinet Screw in the two rack mount screws to attach the Model 6000 mounting brackets to the console cabinet rack Remove the two rear top cover screws see A in figure A 1 Remove the Model 6000 top cover Install the User Bridge Board Do not drop any components inside the Model 6000 If any components are dropped inside the Model 6000 they must be retrieved before power is restored or they may cause serious irreparable damage Do not scrape back plane components or traces while you install the user bridge board Before you install the user bridge board refer to figure A 1 and note the location of the board in the Model 6000 When you face the Model 6000 front panel the user bridge board is at the right rear side of the controller and is immediately adjacent to the system bridge board see D in figure A 1 The user bridge board sits on four posts see C in figure A 1 Complete the following steps to install the user bridge board in the Model 6000 1 Place the user bridge board in the Model 6000 PPMS Resistivity Optio
2. expected power or voltage limit should be specified when first activating a channel The excitation current of an active user bridge channel is limited by the specified maximum excitation current voltage limit or power limit whichever parameter limits the excitation current to a lower value Table 2 6 User Bridge Board Parameters PARAMETER FUNCTION DEFINED BY PARAMETER VALUES Bridge Channel Selected channel on user bridge board 1 4 Current Limit Maximum excitation current for user bridge channel 0 01 5000 pA Power Limit Maximum power for user bridge channel 0 001 1000 UW Voltage Limit Maximum voltage for user bridge channel 1 95 mV Calibration Mode Mode of measuring resistance of sample e Standard s Hi Res e Fast Drive Mode Mode of excitation current applied to sample during e AC eDC resistance measurement PPMS Resistivity Option User s Manual Quantum Design Chapter 2 Section 2 3 User Bridge Board Operation Changing the User Bridge Board Settings While you work with the Resistivity option you will find using the shortcut commands that access the user bridge parameter dialog boxes directly from the control center or the measurement dialog boxes very convenient You may also use standard PPMS MultiVu commands to change user bridge settings The Instrument gt Bridge Channels menu option opens the Bridge Channels dialog box The Bridge Setup sequence command changes user bridg
3. Standard Last measured current and voltage are read to e To compensate for hardware calculate resistance Then adjustment factor is linearity errors drift and used to recalculate and report resistance based on offset errors calibration resistor reading Hi Res Multiple standard mode readings are averaged to e To take high precision maintain uniform precision throughout dynamic measurements range of instrument 2 2 3 1 FAST MODE In fast mode the user bridge board reads the last measured current and voltage to directly calculate the sample resistance and then reports the resistance as quickly as possible without adjusting the reading Fast mode generates the quickest but least accurate measurements and often produces duplicate mea surements Fast mode is useful when resistance measurements are part of a control loop that requires quick feedback 2 4 PPMS Resistivity Option User s Manual Quantum Design Chapter 2 Section 2 2 User Bridge Board Operation Function of the User Bridge Board 2 2 3 2 STANDARD MODE In standard mode the user bridge board reads the last measured current and voltage to measure the sample resistance just as in fast mode but then applies the identical current to an appropriate calibration resistor and measures the potential drop across the resistor with the same gain in order to obtain an adjustment factor The user bridge board then uses this adjustment factor to recalculate and report
4. 2 2 housing user bridge board 1 1 2 1 See also User bridge board Installing illustration of with cover removed A 3 removing cover from A 1 A 2 Multiple resistance measurements taking in immediate mode 3 2 3 6 3 7 in sequence mode 3 2 3 7 3 8 Nominal resolution of user bridge board determining 2 3 Power limit for user bridge board 2 3 2 8 PPMS measurement option deactivating 1 3 PPMS MultiVu application automating Resistivity operation 1 2 commands changing user bridge board settings 2 9 PPMS sample puck sample mounted on illustration of 1 2 using for four wire resistance measurements 1 1 3 2 qd_resistivity_temporary dat file 3 7 PPMS Resistivity Option User s Manual Index 1 Index Resistance bridge board See System bridge board User bridge board Resistance bridge sample holder board wiring sample to 5 2 Resistivity command See Single point resistance measurement Resistivity control center opening with Resistivity option activation 1 3 simplifying system operation 1 3 3 2 Resistivity data files adding comment to 3 11 changing during sequence run 3 11 creating 3 9 3 10 data stored in 3 9 header in and inability to change information written to 3 2 3 9 3 10 opening graph view of 3 4 3 9 required for sequence measurements 3 4 3 7 saving immediate mode data to 3 4 3 7 saving sequence mode data to 3 4 3 5 3 8 3 9 selecting 3 10 Resistivity option adding user bridge
5. 3 Quantum Design Introduction This preface contains the following information e Section P 2 discusses the overall scope of the manual e Section P 3 briefly summarizes the contents of the manual Scope of the Manual Section P 4 illustrates and describes conventions that appear in the manual This manual discusses the operation of the PPMS Resistivity option hardware and software and explains how to take four wire resistance measurements This manual also explains how to use the Resistivity option with the PPMS Helium 3 Refrigerator System and the PPMS Horizontal Rotator Contents of the Manual e Chapter 1 introduces the Resistivity option and discusses the option software e Chapter 2 discusses the functionality of the user bridge board and explains how to operate the user bridge board e Chapter 3 explains how to take four wire resistance measurements Chapter 4 explains how to operate the Resistivity option with the Helium 3 Refrigerator System option Chapter 5 explains how to operate the Resistivity option with the Horizontal Rotator option Appendix A explains how to install the user bridge board in the Model 6000 PPMS Controller PPMS Resistivity Option User s Manual Vil Section P 4 Conventions in the Manual P 4 Preface Contents and Conventions Conventions in the Manual File menu File gt Open STATUS dat lt Enter gt lt Alt Enter gt oO Y Bold text distinguishes t
6. Measure dialog box displays the average temperature magnetic field and sample position used during the measure ment as well as the number of readings taken and the elapsed time of the measurement The actual number of readings taken during the measurement is shown in the Actual Readings panel PPMS Resistivity Option User s Manual Quantum Design Chapter 3 Section 3 3 Four Wire Resistance Measurements Taking Four Wire Resistance Measurements 11 Select the View button in the Scan Excitation Quick Measure dialog box if you want to open the qd_resistivity_temporary dat file and see a plot of the measurement View opens the file only when a Resistivity data file is selected to store data and a multiple point resistance measurement has just been run in immediate mode The qd_resistivity_temporary dat file is overwritten each time another multiple point resistance measurement runs in immediate mode 12 Select the Save button in the Scan Excitation Quick Measure dialog if you want to save the measurement results to the specified data file You must select Save in order to save the data The Save button is disabled after you select it and remains disabled until another multiple point resistance measurement runs The button is also disabled if a data file has not been not selected 13 Select Close if you want to close the Scan Excitation Quick Measure dialog box 3 3 2 2 TAKING MEASUREMENTS IN SEQUENCE MODE After you insert the sample into
7. Quick Measure x r Control een ey P Results rri Channel Estimated Excitation Resistivity Temperature K ma Timelsec fas fi Ohm fa 13 3333 S 2 es 1 686 Ohm Field De 6574 5 T 3 Readings Ohm Position det l Actual Elapsed Baas se Readings 25 reai l Figure 3 3 Resistivity Quick Measure Dialog Box Select the Channel check boxes representing the user bridge channels you want to read Any number of channels may be read If you select channels to which no sample is wired a value of zero is reported when the measurement is complete Enter in the Readings text box the number of readings you want the system to take and average for one measurement The readings are averaged regardless of the calibration mode so if the channel uses high resolution mode see section 2 2 3 3 the operations specific to that mode are performed first before the Resistivity software averages the readings Select the Bridge Setup button if you want to review or change user bridge settings A channel must be active to be measured Section 2 3 explains how you change user bridge settings Select Measure The measurement begins The Measure button reads Cancel during the mea surement You select Cancel to abort the measurement When the measurement is complete the Resistivity Quick Measure dialog box displays the measurement results as well as the average temperature magnetic field and sam
8. Resistivity Option User s Manual Quantum Design Contents Table of Contents APPENDIX A Teta a ete hd ee eh Sat hd eet E al Ee A 1 Ash B Sele Te ST A 1 A2 Installing the User Bridge Board PT A 1 A 2 1 Remove the Model 6000 Covet sss eee A 1 A22 Install the User Bridge Boards TTT A 2 Refer OT References 1 T OX ENET O ESEE E OEN i E EL OENE ie EEE ONET EA Index 1 Quantum Design PPMS Resistivity Option User s Manual m Contents Table of Figures Figures Figure 1 1 Figure 1 2 Figure 1 3 Figure 1 4 Figure 2 1 Figure 2 2 Figure 2 3 Figure 2 4 Figure 2 5 Figure 3 1 Figure 3 2 Figure 3 3 Figure 3 4 Figure 3 5 Figure 3 6 Figure 3 7 Figure 3 8 Figure 3 9 Figure 4 1 Figure 4 2 Figure 5 1 Figure A 1 Interface on Resistivity Sample PUCK irrena e a e a e S 1 1 Example of Four Wire Resistance Measurement cssccesececeesceeseeeseeeeeeeeceeeeeceeeceeeeseeeeeeeeeneeeas 1 2 Option Manager Dialog TTT 1 2 Resistivity Control Cemtercss ciesss sasccestestescbeeeecesodeabesdepes tense ieee e aids eea e eie due arire ei RERE S 1 3 Block Diagram of Bridge Board pssi asair a ase ee T ee een a ap tee daia 2 3 Number of Measurements Averaged in High Resolution Mode sss sese 2 6 Bridg Channels Dialog Box neredne Neta TSS E E a ees 2 9 Bridge Configuration Tab in Resistivity Dialog BOX sese eee 2 10 Allowed Measurement Parameters V and L sss essen 2 12 Resistivity Sample Puck with
9. Three Samples esse sees ee eee 3 1 Resistivity Control Center anara uaren EES To Handed ae e tasa E ren a To aug SEN agio ai 3 2 Resistivity Quick Measure Dialog BOX sss 3 3 Bridge Configuration Tab in Resistivity Dialog BOX sese 3 4 Data Fields Tab in Resistivity Dialog BOX sese sese 3 5 Scan Excitation Quick Measure Dialog BOX sss sese 3 6 Scan Setup Tab in Scan Excitation Dialog Boxes esse 3 7 File and Sample Properties Dialog BOX sss 3 10 Datafile Comment Dialog Box for Immediate Mode sss 3 11 User Bridge TTT 4 2 Helium 3 Sample Puck with Two Samples sees ee ee eee eee eee 4 3 Resistance Bridge Sample Holder Board with Two Samples sss sse eee eee 5 2 Model 6000 PPMS Controller with Cover Removed sss A 3 PPMS Resistivity Option User s Manual Quantum Design Contents Tables Table 2 1 Table 2 2 Table 2 3 Table 2 4 Table 2 5 Table 2 6 Table of Tables Sample Connections with User Bridge Cable Connected sss esse sese eee 2 2 Current Power and Voltage Limits TT 2 3 Current Ranges oseese istorii ess te e Sous EERE KEE DEAE EEEE Ssh and EE de vides ees Agius ae VEE eise e 2 4 Function and Suggested Use of Calibration Modes sss sss 2 4 NV Oltdge Gain SENES a r a r aa a a Ea a a AE st a Eo aE ER SaR EEEo 2 7 User Bridge Board Parameters soc soeren ee eee p oe nane nae ap reaa EE es SEESE aUe iya 2 8 Quantum Design PPMS Resistivity Option User s Manual N P R E F A C E Contents and Conventions P 1 P 2 P
10. board to system 1 1 See also User bridge board electrical connections 2 2 measurement types reported by 1 1 operation with Helium 3 Refrigerator System See Helium 3 Refrigerator System option operation with Horizontal Rotator See Horizontal Rotator option sample pucks used with 1 1 See also PPMS sample puck Resistivity sample puck Resistivity option software See also Resistivity control center Resistivity data files activating 1 2 1 3 default data recorded by 3 9 Resistivity sample puck interface description of 1 1 3 1 as platform for up to three samples 1 1 3 1 3 2 samples mounted on illustration of 3 1 wiring sample to 1 1 3 1 3 2 Sample and association with one user bridge board channel 3 1 3 2 3 9 wiring for four wire resistance measurement See Helium 3 sample mount PPMS sample puck Resistance bridge sample holder board Resistivity sample puck Sample resistance estimating before measurement 2 8 3 2 Scan Excitation command in immediate mode using 3 6 3 7 in sequence mode function of 3 7 Single point resistance measurement taking in immediate mode 3 2 3 3 3 4 in sequence mode 3 2 3 4 3 5 Standard mode See also Fast mode Index 2 PPMS Resistivity Option User s Manual calculating sample resistance in 2 4 2 5 See also User bridge board Operation as default calibration mode 2 4 suggested usage 2 4 as user bridge board parameter 2 4 2 8 Standard sample puck See
11. ja Data Flags Value 255 Figure 3 5 Data Fields Tab in Resistivity Dialog Box Enter in the Reading Count text box the number of readings you want the system to take and average for one measurement The readings are averaged regardless of the calibration mode so if the channel uses high resolution mode see section 2 2 3 3 the operations specific to that mode are performed first before the Resistivity software averages the readings Select OK to add the Resistivity command to the sequence Select the Save Sequence File button in the PPMS MultiVu tool bar type a file name for your sequence and then select Save in the pop up dialog box Select the Run Sequence button in the PPMS MultiVu tool bar You saved your new sequence and selected a data file so the sequence should run immediately Status messages in the PPMS MultiVu interface indicate that a sequence is running The commands in the sequence determine the length of time the sequence runs The Resistivity command you included in the sequence is executed when it is read during the sequence run PPMS Resistivity Option User s Manual 3 5 Section 3 3 Chapter 3 Taking Four Wire Resistance Measurements Four Wire Resistance Measurements 3 3 2 3 6 Taking Multiple Resistance Measurements The Scan Excitation command which takes resistance measurements throughout a specified excita tion range can be executed immediately from the PPMS MultiVu Measure menu or it can be in
12. significantly affect the sample Section 2 2 4 discusses the drive modes in detail 8 Select the enabled Set button for each channel in order to put the changes you have made into effect Changes to all other controls including deactivating the Channel On check box are initiated only when you select Set 9 Select Close if you want to close the Bridge Channels dialog box 2 3 2 Using the Bridge Configuration Tab to Change Bridge Settings 1 Select the Bridge Configuration tab in the Resistivity or Scan Excitation dialog box These dialog boxes open only when the Resistivity or Scan Excitation sequence mode command is selected Refer to sections 3 3 1 2 and 3 3 2 2 for information on sequence mode measurements Resistivity Ea Bridge Configuration Data Fields Channel Current Limit Power Limit Voltage Limit Calibration Drive Set u uw mi Mode Mode 1 fon z fico Standard x Jac 7 Standard Y Standard zj 4c T K for x fica Figure 2 4 Bridge Configuration Tab in Resistivity Dialog Box 2 Use the Channel Set pull down menu to activate the user bridge channel or channels whose parameter settings you want to change The text boxes and menus are enabled only when the corresponding channel is activated The No Action option in the Channel Set pull down menu prevents the state of a channel from being altered The Off option deactivates the channel 3 Set the maximum excitation current for each channel as neces
13. the sample resistance By utilizing calibration resistors whenever possible standard mode compensates for hardware linearity errors drift and offset errors However consulting a calibration resistor to complete most readings means that the user bridge channels update more slowly If the user bridge settings prohibit use of a calibration resistor the measured values are not adjusted when the resistance is reported This situation might arise for example when the sample resistance is either too small or too large to be used in conjunction with a calibration resistor without adjusting the gain setting If the uppercase S which denotes the standard mode setting on the Model 6000 front panel display changes to a lowercase s the reported value was not adjusted and is therefore equivalent to a reading taken in fast mode When operating in standard mode the user bridge stores any adjustment factors used and reuses them for resistance calculations whenever identical measurement conditions occur on any channel within the next minute This eliminates repetitive measurement of the calibration resistors These adjustment factors are updated after one minute and are erased when an abort is executed when a CAL GPIB command is requested or when the power is turned off 2 2 3 3 HIGH RESOLUTION MODE In high resolution mode the user bridge board averages multiple standard mode readings in order to maintain uniform precision throughout the ran
14. Bridge Sela and cannot be changed in PPMS MultiVu If you change the samples on a puck insert a new puck _Messue _ or wire a sample to some other channel you must create a new data file to ensure that the integrity Figure 3 2 Resistivity Control of the stored data is maintained Center PPMS Resistivity Option User s Manual Quantum Design Chapter 3 Section 3 3 Four Wire Resistance Measurements Taking Four Wire Resistance Measurements 3 3 1 Taking Single Point Resistance Measurements The Resistivity command which takes one resistance measurement at the current system conditions can be executed immediately from the Resistivity control center or the PPMS MultiVu Measure menu or it can be included in a sequence 3 3 1 1 TAKING MEASUREMENTS IN IMMEDIATE MODE After you insert the sample into the sample chamber and select the data file see section 3 3 you can define and then run the measurement Complete the following steps 1 Quantum Design Select the Measure button in the Resistivity control center or select the Resistivity option in the Measure menu The Resistivity Quick Measure dialog box opens Items in the Control panel on the left side of the dialog box designate measurement conditions that should be set prior to running the measurement Items in the Results panel on the right side of the dialog box display the results of the last single point resistance measurement that was run in immediate mode Resistivity
15. PPMS sample puck System bridge board 2 1 User bridge board adjusting excitation current 2 1 2 3 2 4 2 11 block diagram 2 3 calibration modes 2 4 2 8 See also Fast mode High resolution mode Standard mode channels See User bridge board channels drive modes 2 6 2 7 2 8 electrical connections 2 2 enabling four wire resistance measurements 1 1 2 1 See also Four wire resistance measurements installing A 1 A 3 internal voltage gain control 2 1 2 7 location in Model 6000 PPMS Controller illustration of A 3 as main component of Resistivity option 1 1 2 1 operation description of 2 11 2 12 See also User bridge board channels Changing settings parameters changing See User bridge board channels Changing settings list of 2 8 See also AC mode DC mode Fast mode High resolution mode Standard mode User bridge board channels changing settings for in immediate mode 2 8 2 9 2 10 with Model 6000 PPMS Controller 2 11 in sequence mode 2 8 2 9 2 10 2 11 number of available 1 1 parameters list of 2 8 See also AC mode DC mode Fast mode High resolution mode Standard mode User bridge cable illustration of 4 2 used with Helium 3 Refrigerator System 4 1 4 2 used with Horizontal Rotator 5 1 5 2 UserTemp turning off 5 3 Voltage limit for user bridge board 2 3 2 8 Voltage gain settings for user bridge board 2 7 Quantum Design
16. QuantumDesign pa wi all aall Physical Property Measurement System Resistivity Option User s Manual Part Number 1076 100A Quantum Design 11578 Sorrento Valley Rd San Diego CA 92121 1311 USA Technical support 858 481 4400 800 289 6996 Fax 858 481 7410 Second edition of manual completed August 1999 Trademarks All product and company names appearing in this manual are trademarks or registered trademarks of their respective holders U S Patents 4 791 788 Method for Obtaining Improved Temperature Regulation When Using Liquid Helium Cooling 4 848 093 Apparatus and Method for Regulating Temperature in a Cryogenic Test Chamber 5 311 125 Magnetic Property Characterization System Employing a Single Sensing Coil Arrangement to Measure AC Susceptibility and DC Moment of a Sample patent licensed from Lakeshore 5 647 228 Apparatus and Method for Regulating Temperature in Cryogenic Test Chamber 5 798 641 Torque Magnetometer Utilizing Integrated Piezoresistive Levers Foreign Patents U K 9713380 5 Apparatus and Method for Regulating Temperature in Cryogenic Test Chamber c ONTENTS Table of Contents PREFACE Contents and Conventions eee eee vii Pet IO GUCH TTT vil P 2 Scope of the Manual c 40 see Riss Asatiaien Avila abt diate iar Arh Alavi Areas beanie aa aE eanan ayes vii P 3 Contents of the Manualne seiso oiris A sobiue ta conse eroek E cuvens Ads EKE casas se OOE Ages aus te cust EE SEEE aek e
17. The nominal resolution of the user bridge board is determined by the resolution of the A D converter and by the maximum applicable current Accordingly nominal resolution on the most sensitive range is 3 81 nV 5 00 mA 0 762 uQ In practice environmental and internal noise sources usually limit measurement precision to around 20 nV or 4 uQ with a 5 mA excitation Measurement resolution also depends on the internal gain setting and the excitation current which can be affected by the resistance being measured and by the specified limits for current power and voltage The maximum measurable resistance is computed from the maximum potential drop that can be measured and from the minimum useful excitation current which is determined by the user bridge s DAC resolution The nominal maximum measurable resistance is thus 95 mV 2 44 nA 38 9 MQ However such a measurement would require an excitation current very near the DAC resolution In practice user bridge board error increases drastically above approximately 4 MQ Errors in excess of 1 can be anticipated when measuring resistances greater than 4 MQ The expected error increases to 5 10 around 9 MQ The parameter ranges in this section represent the broadest limits Current limitations set by the user specified current power or voltage limit can alter these values 2 3 PPMS Resistivity Option User s Manual Section 2 2 Chapter 2 Function of the User Bridge Board User Bridge Board Ope
18. To open the Setup Bridge Channel screen you select the STATUS BRIDGE screen and then select setup or you enter the CONTROL menu and select 3 Immediate Operations gt 06 Bridge In the Setup Bridge Channel screen you press incr and decr to choose a bridge channel Then you adjust the current limit power limit voltage limit calibration mode and drive mode as necessary Once the settings are correct press EXEC lt Alt Enter gt to execute them The Model 6000 STATUS BRIDGE screen normally displays the status including resistance excitation current calibration mode and drive mode of each user bridge channel However you can configure the Model 6000 to show the status of the system bridge board channels and calibration channels To do this enter the CONFIG menu and select 5 Software Then select 3 Diagnostics and change the Bridge Display Channel setting to the appropriate display The standard setting displays the four user bridge channels Once this display is reconfigured it becomes possible to change system bridge settings simply by selecting setup from the STATUS BRIDGE screen Note though that because these channels are used for PPMS temperature control changing their settings is not recommended 2 4 Description of User Bridge Board Operation After any new user bridge board channel settings are executed excitation current is applied to each active channel beginning with the lowest numbered channel If a channel was operating b
19. ance before taking measurements and for delicate samples expected to have resistances greater than 1 KQO only a current limit that will not exceed the samples expected power or voltage limit should be specified when first activating a channel Before you measure resistance you must 1 mount the sample on a puck and wire the sample to a user bridge channel 2 insert the sample into the sample chamber by selecting the Install Remove button in the Resistivity control center and following the pop up instructions and 3 select or create a new Resistivity data file if necessary Section 3 2 explains how you mount samples on Resistivity pucks Section 3 4 1 explains how you create a data file Section 3 4 2 explains how you select a data file For all normal system operations installing samples selecting data files and taking immediate mode measurements you are j Semele Status encouraged to use the Resistivity control center The auto P Installed Instal Remove mated routines in the control center help ensure that you Samples complete the necessary procedures when you install samples a 7 E or create data files The examples of measurements in this Datafile chapter illustrate use of the control center C QdPpms Data NewResData dat View Each sample is associated with one user bridge board channel The sample s association with a specific channel is identified in the data file header
20. art saving Resistivity measurement data and the selected system parameter data to the new data file specified by the command You can use Change Datafile to select an existing data file or to create a new data file Complete the following steps to change data files during a sequence run 1 Position the highlight bar in the sequence editor so that the highlight bar marks the location where you want to insert the Change Datafile command New commands are inserted immediately above the highlight bar Refer to the Physical Property Measurement System PPMS MultiVu Application User s Manual for detailed information about sequence operation 2 Select the Change Datafile command in the Measurement Commands group that is in the sequence command bar The Change Datafile Sequence dialog box opens and displays the Datafile tab 3 Select Browse The Select a Data File dialog box opens The dialog box lists all existing data files 4 Select or create a data file as necessary Refer to sections 3 4 1 and 3 4 2 As soon as you select or create a file you see the Datafile tab in the Change Datafile Sequence dialog box again The tab shows the file location and name of the data file you have just selected 5 Ifyou are selecting a data file use the Sample tab in the Change Datafile Sequence dialog box to determine whether you have selected an appropriate data file for your sample If the file stores data for some other sample or for some other sample wiri
21. ation automatically occurs after the abort command is received Requesting a calibration temporarily interrupts the flow of data and the Model 6000 s control of other devices for approximately 0 5 second For highest data integrity a calibration should be performed before running each experiment that requires precision data Requesting a calibration affects all PPMS A D converters and can theoretically introduce data offsets if performed between measurements Quantum Design PPMS Resistivity Option User s Manual Section 2 3 Chapter 2 Changing the User Bridge Board Settings User Bridge Board Operation 2 3 VY CAUTION oC NOTE 2 8 Changing User Bridge Board Settings The Resistivity software includes multiple ways to access dialog boxes that can be used to change the current user bridge board channel settings The Resistivity control center and the Resistivity and Scan Excitation immediate mode measurement commands can directly open the Bridge Channels dialog box The Resistivity and Scan Excitation sequence mode measurement commands open dialog boxes that include a Bridge Configuration tab The Bridge Channels dialog box figure 2 3 shows the parameter settings for all four channels on the user bridge and indicates whether each channel is active If a channel is active the Bridge Channels dialog displays the current and resistance the user bridge is measuring across that channel An active channel is always running and pass
22. cluded in a sequence Resistance measurements taken with Scan Excitation are actually taken one at a time although the measurements may be read so rapidly they appear to be taken simultaneously 3 3 2 1 TAKING MEASUREMENTS IN IMMEDIATE MODE After you insert the sample into the sample chamber and select the data file see section 3 3 you can define and then run the measurement Complete the following steps 1 10 Select Measure gt Scan Excitation The Scan Excitation Quick Measure dialog p Conta Sten J Channel p Excitation Temperature K 4 Initial fioo IEE box opens Items in the Control panel on the left side of the dialog box designate mea Field 0e ies i i Field Oe surement conditions that should be set prior FT o S fas to running the measurement Items in the Deta 4900 i PER 2 s PT System panel on the right side of the dialog steps P o box indicate what the values of key system C4 O E EE parameters were during the last multiple JIS point resistance measurement run in Readings Step _EstimatedTime sec Elapsed Timefsec immediate mode 25 26 6667 o Select the Channel option representing the BES user bridge channel you want to read Use the Initial text box to specify the View starting current in the excitation range Notice that when you change the excitation range the value of Delta which is the Figure 3 6 Scan Excitation Quick Meas
23. ction 2 3 explains how you change user bridge settings When you use the Resistivity sequence command to activate user bridge channels the resistivity and excitation read off the activated channels are saved to the data file and the data items for the activated channels are automatically selected in the Data Fields tab see figure 3 5 When a user bridge channel is deactivated that is set to Off no data can be collected for that channel PPMS Resistivity Option User s Manual Quantum Design Chapter 3 Section 3 3 Four Wire Resistance Measurements Taking Four Wire Resistance Measurements 2 Quantum Design Use the Data Fields tab to select the system data items you want to save to the data file By default the general system status temperature magnetic field and sample position are selected to be saved The resistivity and excitation read off the active channels are also saved to the file Bridge Configuration Data Fields IV General Status E Brg Ch 1 Resistivity I Map 20 M Temperature V Brg Ch 1 Excitation T Map 21 IV Magnetic Field E Brg Ch 2 Resistivity T Map 22 lV Sample Position I7 Brg Ch 2 Excitation T Map 23 T Sample Pressure T Brg Ch 3 Resistivity T Map 24 T DrCh 1 Current T Brg Ch 3 Excitation T Map 25 I DrCh 1 Power T Brg Ch 4 Resistivity T Map 26 T DrCh 2 Current T Brg Ch 4 Excitation T Map 27 I DrCh 2 Power T Sig Ch 1 Input Voltage T Map 28 T Digital Inputs T Sig Ch 2 Input Voltage T Map 29 Reading Count
24. d 3 are available for resistance measurements The standard user bridge cable part number 3084 003 is connected to both the gray ringed Lemo connector on the PPMS probe head and the P1 User Bridge port on the Model 6000 PPMS Con troller when the Resistivity option is used with the Horizontal Rotator Figure 4 1 illustrates the user bridge cable Quantum Design PPMS Resistivity Option User s Manual 5 1 Section 5 3 Chapter 5 Resistivity Measurements with the Horizontal Rotator Operation with the Horizontal Rotator 5 3 5 3 1 V CAUTION Resistivity Measurements with the Horizontal Rotator Please refer to the Physical Property Measurement System Horizontal Rotator Option User s Manual for complete instructions on handling and operating the PPMS Horizontal Rotator Measurement Setup 5 3 1 1 PREPARE FOR THE MEASUREMENT 1 Install the user bridge cable see figure 4 1 by plugging the connectors on the cable into the ports indicated by the cable labels Plug the 14 pin gray Lemo connector into the gray color coded port on the probe head Plug the 25 pin connector labeled P1 User Bridge into the P1 User Bridge port on the rear of the Model 6000 5 3 1 2 INSTALL THE SAMPLE 1 Mount the sample on a resistance bridge sample holder board part number 3084 371 2 Refer to figure 5 1 to wire the sample to the sample holder board The sample holder board is clearly labeled for mountin
25. d in the usual way that is between the gray ringed Lemo connector on the PPMS probe head and the P1 User Bridge port on the Model 6000 PPMS Controller Because channel 3 is used for thermometry only channels 1 and 2 are available for measurements Quantum Design PPMS Resistivity Option User s Manual 4 1 Section 4 3 Chapter 4 Resistivity Measurements with the Helium 3 System Operation with the Helium 3 System 4 3 Resistivity Measurements with the Helium 3 System Please refer to the Physical Property Measurement System Helium 3 Refrigerator System User s Manual for complete instructions on handling and operating the PPMS Helium 3 system 4 3 1 Measurement Setup 4 3 1 1 PREPARE FOR THE MEASUREMENT while you are inserting the refrigerator probe into or removing it from the PPMS sample chamber The material out of which the probe shaft is constructed is thin and fragile and can easily bend or dent WV Avoid stressing the shaft of the Helium 3 refrigerator probe in any way CAUTION 1 Remove the Helium 3 refrigerator probe from the sample chamber Refer to the Physical Property Measurement System Helium 3 Refrigerator System User s Manual for detailed instructions 2 Quit the Helium 3 software application if the application is running 3 Install the user bridge cable part number 3084 003 by plugging the connectors on the cable into the ports indicated by the cable labels Plug the 14 pin gray Lemo connector in
26. e board is essentially nonconfigurable Three of its four channels are dedicated to system thermometry and the fourth channel is reserved for other PPMS options Consequently the user bridge board must be installed to take four wire resistance measurements Quantum Design PPMS Resistivity Option User s Manual 2 1 Section 2 2 Function of the User Bridge Board Sample Puck BOTTOM VIEW Gray Lemo Connector Chapter 2 User Bridge Board Operation Table 2 1 Sample Connections with User Bridge Cable Connected P1 User Bridge Port 131211109 876543 21 Oo0o0o0000000000 Oo0o0o000000000 25 2423222120 1918171615 14 The sample connector is at the bottom of the sample chamber The gray Lemo connector is on the probe head Pins 1 and 2 on the gray Lemo connector are connected to wires that extend into the annulus system expansion The P1 User Bridge D connector is on the Model 6000 These wires are not used for any function but provide a site for SAMPLE SAMPLE GRAY LEMO P1 USER BRIDGE USER BRIDGE BOARD PUCK CONNECTOR CONNECTOR D CONNECTOR FUNCTION 1 Cur Driver 1 unused 14 Cur Driver 1 unused 2 Cur Driver 2 unused 15 Cur Driver 2 unused 3 3 3 S Channel 1 I 4 4 4 18 Channel 1 I 5 5 5 6 Channel 1 V 6 6 6 19 Channel 1 V 7 7 7 7 Channel 2 I 8 8 8 20 Channel 2 9 9 9 8 C
27. e settings within a running sequence These two PPMS MultiVu commands function only if a user bridge board is installed in the Model 6000 Refer to the Physical Property Measurement System PPMS MultiVu Application User s Manual for a detailed discussion of all PPMS MultiVu commands and operations 2 3 1 Using the Bridge Channels Dialog Box to Change Bridge Settings 1 Quantum Design Select the Bridge Setup button in the Resistivity control center or in the Resistivity Quick Measure or Scan Excitation Quick Measure dialog box The Bridge Channels dialog box opens The Resistivity software gives you the option to review or change user bridge settings at any time Selecting Bridge Setup in the measurement dialog boxes lets you change user bridge settings while you are defining a measurement You may close the Resistivity Quick Measure or Scan Excitation Quick Measure dialog box and keep the Bridge Channels dialog box open Bridge Channels Eg Control roofs Channel Current Power Limit Voltage Limit Calibration Drive S D ON Unai uw mv Made Made d mhd poo foo Tsandad fac 2 451 000 3092 36597 2 fano moo po stndia SRC z a 451 000 2664 98193 3 M s3380 2438000 feo standard lC A oe 451 000 0 50700 4M s390 fesso f0 stondaa lar oe 451 000 8 03700 0 01 5000 0 001 1000 1 0 95 0 Close Figure 2 3 Bridge Channels Dialog Box Verify that the user bridge channel or channels whose param
28. e the potential difference across the sample figure 1 2 The voltmeter has a very high impedance so the voltage leads draw very little current In theory a perfect voltmeter Figure 1 2 Example of four draws no current whatsoever Therefore by using the four wire wire resistance measure method it is possible to know to a high degree of certainty both ment with sample mounted the current and the voltage drop across the sample and thus on standard PPMS sample calculate the resistance with Ohm s law puck 1 3 Resistivity Option Software The Resistivity option software is automatically installed when the PPMS MultiVu software applica tion is installed on the control PC and the Resistivity software is fully integrated into PPMS MultiVu so PPMS MultiVu commands can be used to automate Resistivity system operation However before the Resistivity option can be used the Resistivity software must be activated within PPMS MultiVu Only one measurement option may be active at a time in PPMS MultiVu so you might have to deacti vate another measurement option before you can activate the Resistivity option Refer to section 1 3 1 1 3 1 Activating the Resistivity Software 1 Select the Utilities gt Activate Option menu command in PPMS MultiVu The Option Manager dialog box opens The dialog box lists all options that are available on your PPMS and indicates whether each option is active 2 Select Resistivity in the Available Op
29. ections for the Resistivity option Appendix A in the Physical Property Measurement System Hardware Manual identifies all electrical connections used in a standard PPMS The user bridge board has several essential elements as shown in figure 2 1 on page 2 3 A 12 bit 11 bit sign digital to analog converter DAC adjusts the excitation current up to 5 mA The current range and channel selection are performed internally A 20 bit delta sigma A D converter reads the voltage output of the variable gain stage The bridge board s A D converter contains 50 Hz and 60 Hz notch filters to reject line noise In addition a set of 0 01 bulk metal foil resistors is used internally as calibration resistors In January 1996 a new feature was added to the user bridge board The negative current leads for each channel which were previously tied directly to a common ground were switched in and out of the measurement circuit like the rest of the leads This modification allows multiple channels to be connected to the same sample without shorting out the excitation signal User bridge boards assembled prior to 1996 do not have this capability In addition to the user bridge board all PPMS units include another resistance bridge board called the system bridge board that is installed behind the P2 System Bridge port on the Model 6000 PPMS Controller The operation of the system bridge board and user bridge board is nearly identical but the system bridg
30. efore the new configuration was executed the user bridge assumes that the resistance has not changed in order to predict the measurement parameters I and V and set the initial excitation current The initial excitation current is usually the specified current limit If this current would cause the power to exceed the specified power limit with a 1 kQ resistance the user bridge uses a 1 kQ initial resistance estimate for the first cycle of an approach algorithm Accordingly a settling time of a few seconds may be required to reach a stable excitation current This can be another important consideration when writing sequence files At equilibrium the excitation current equals the current limit setting unless the power limit setting or voltage limit setting is reached It is important to understand the range of possible excitation currents and potential drops across the sample You choose the maximum allowable current voltage and power through the sample so measurement parameters are confined to the dark lines in the graph in figure 2 5 When the power limit is set greater than 460 uW only the current and voltage limit settings should affect the measurement parameters Quantum Design PPMS Resistivity Option User s Manual 2 1 1 Section 2 4 Chapter 2 Description of User Bridge Board Operation User Bridge Board Operation The voltage drop across the sample is read twice with the same polarity excitation each time for DC mode and with opposite
31. erty Measurement System Horizontal Rotator Option User s Manual for detailed instructions 2 Engage the rotator motor and check for the proper position calibration Refer to the Physical Property Measurement System Horizontal Rotator Option User s Manual for detailed instructions 5 3 2 Performing Measurements Once the Horizontal Rotator probe is inserted in the sample chamber and the Resistivity software application is running you may take resistance measurements as you would normally Refer to chapter 3 5 3 3 Turning Off UserTemp Configuring the Horizontal Rotator by transmitting the configuration files to the Model 6000 ROM also turns on UserTemp so that the rotator thermometer is used for temperature control When you complete your experiments with the Horizontal Rotator and remove the Horizontal Rotator probe from the sample chamber you should turn off this thermometer Complete the following steps 1 Open Monitor QD 6000 in the PPMS 32 bit Tools folder or select Utilities gt Send GPIB Commands in the PPMS MultiVu interface 2 Type USERTEMP 0 3 Press lt Enter gt to execute this command If you do not turn off UserTemp the resistance read off user bridge channel is used to control the temperature in the sample chamber If UserTemp remains on but no user thermometer is installed that is the Horizontal Rotator probe is removed from the PPMS the temperature control defaults back to the system ther
32. eter settings you want to change are activated Activate channels as necessary by clicking on the appropriate Channel On check boxes so that a check mark appears in the check boxes In figure 2 3 all four channels are activated If you want to deactivate a channel click once on the appropriate Channel On check box so that the check mark disappears Set the maximum excitation current for each channel as necessary Specifying a current limit of zero for any channel deactivates the channel Table 2 6 and the Bridge Channels dialog box identify the acceptable parameter ranges Notice that as soon as you change a parameter value for any channel the channel s Set button in the Bridge Channels dialog box is enabled Set the power limit for each channel as necessary Specifying a power limit of zero for any channel deactivates the channel Set the voltage limit for each channel as necessary PPMS Resistivity Option User s Manual 2 9 Section 2 3 Chapter 2 Changing the User Bridge Board Settings User Bridge Board Operation 6 Select the calibration mode the channel uses to measure sample resistance The standard fast and high resolution modes are available Section 2 2 3 discusses the calibration modes in detail Table 2 4 suggests possible uses for each mode 7 Select the drive mode the channel uses during the resistance measurement The AC and DC drive modes are available You are advised to use AC mode unless reversing polarity would
33. eturn to step 2 and select another data file 4 Select OK to close the File and Sample Properties dialog box and to prompt the Resistivity software to store all new measurement data in the selected data file 3 10 PPMS Resistivity Option User s Manual Quantum Design Chapter 3 Section 3 4 Four Wire Resistance Measurements Resistivity Data Files 3 4 3 Adding a Comment to a Resistivity Data File You can append a comment containing any number of characters to the selected Resistivity measure ment data file Because the comment is appended to only the selected data file you should first verify that the file to which you want to append the comment is selected In immediate mode you append a comment to a data file by selecting the Measure Add Datafile Comment menu option entering the comment in the pop up dialog box and then selecting OK In sequence mode you select the Datafile Comment measurement sequence command enter the comment and then select OK You may add only a comment to a data file you may not insert a blank line into a data file Datafile Comment Eg Current datafile iC QdPpms Data NewResD ata dat Comment Enter your comment here OK Cancel Figure 3 9 Datafile Comment Dialog Box for Immediate Mode 3 4 4 Changing Resistivity Data Files during a Sequence Run The Resistivity option includes the Change Datafile sequence command When the Change Datafile command is executed it prompts the system to st
34. for See Horizontal Rotator option saving data from See Resistivity data files taking multiple in immediate mode 3 2 3 6 3 7 in sequence mode 3 2 3 7 3 8 taking single point in immediate mode 3 2 3 3 3 4 in sequence mode 3 2 3 4 3 5 user bridge board channels available for 3 1 3 2 wiring sample for See Helium 3 sample mount PPMS sample puck Resistance bridge sample holder board Resistivity sample puck Helium 3 refrigerator probe proper handling of 4 2 Quantum Design Helium 3 Refrigerator System option extending temperature range 4 1 4 4 and possible cross talk 4 4 reserving user bridge board channel 3 4 1 4 4 taking four wire resistance measurements when installed 4 2 4 4 user bridge board channels available with 4 1 Helium 3 sample mount wiring sample to 4 3 High resolution mode See also Standard mode calculating sample resistance in 2 4 2 5 2 6 See also User bridge board Operation suggested usage 2 4 as user bridge board parameter 2 4 2 8 Horizontal Rotator option and function of UserTemp 5 3 reserving user bridge board channel 1 5 1 rotating samples 5 1 taking four wire resistance measurements when installed 5 2 5 3 user bridge board channels available with 5 1 Horizontal Rotator probe proper handling of 5 2 Measurements See Four wire resistance measurements Model 6000 PPMS Controller changing user bridge board settings with 2 11 connections for P1 User Bridge port
35. g two samples 3 Attach the sample holder board to the rotator transfer case Refer to the Physical Property Measurement System Horizontal Rotator Option User s Manual for detailed instructions The Horizontal Rotator probe is delicate and must be handled with care Use caution so that you do not dent or bend the stainless steel tube on the Figure 5 1 Resistance bridge outside of the probe Be extremely careful when sample holder board with two placing the probe on a flat surface such as a table samples mounted for four wire because the probe may easily roll off resistance measurements 4 Insert the Horizontal Rotator probe into the sample chamber Refer to the Physical Property Measurement System Horizontal Rotator Option User s Manual for detailed instructions PPMS Resistivity Option User s Manual Quantum Design Chapter 5 Section 5 3 Operation with the Horizontal Rotator Resistivity Measurements with the Horizontal Rotator 5 3 1 3 START UP THE SOFTWARE Start up PPMS MultiVu if the application is not running 2 Activate the Resistivity option in PPMS MultiVu Do the following a select Utilities gt Activate Option b click on Resistivity under the Available Options heading and then c select the Activate button 5 3 1 4 CONFIGURE THE ROTATOR 1 Download the appropriate configuration file for the rotator in order to set up the rotator thermometry and configure the rotator motor Refer to the Physical Prop
36. ge of readings High resolution mode helps eliminate noise from the readings and generates the most accurate but slowest resistance measurements If the user bridge settings prohibit use of a calibration resistor unadjusted values are averaged The upper case H which denotes the high resolution mode setting on the Model 6000 front panel display changes to a lowercase h to indicate that unadjusted values are averaged The number of standard mode readings averaged to yield the reported resistance in high resolution mode varies from 2 to 16 and depends on the divergence of the measured resistance from a base value of 32 767 Q The further the resistance is from the base value the more standard mode readings are averaged to obtain the value reported The number of readings averaged can be defined as Te N Int aa 26 2 mQ lt R lt 0 5 MQ og N 16 R lt 2mQ or R gt 0 5 MQ where R is the sample resistance For resistances between 16 4 Q and 65 5 Q only two standard mode readings are averaged Resistances greater than about 0 5 MQ or less than 2 mQ require 16 readings as seen in figure 2 2 For small resistances this averaging helps eliminate noise due to a small voltage readback and for large resistances it helps eliminate noise due to the low applied current A measure ment that averages 16 readings takes 7 5 Hz x 16 2 13 seconds Such considerations can be important when writing a sequence file that involves data acquisitio
37. hannel 2 V 10 10 10 21 Channel 2 V 11 11 11 9 Channel 3 I 12 12 12 22 Channel 3 I 13 13 13 10 Channel 3 V 14 14 14 23 Channel 3 V 11 Channel 4 I 24 Channel 4 I 12 Channel 4 V 25 Channel 4 V 13 Shield PPMS Resistivity Option User s Manual Quantum Design Chapter 2 User Bridge Board Operation Section 2 2 Function of the User Bridge Board CHANNEL SELECT nO Zu mmz ours zuOD EXCITATION DAC wD RI 20 CALIBRATION RESISTORS R2 200 pve R3 eve T eov 2k CONTROL 20K PROGRAMMABLE GAIN A D CONVERTER HEATER DRIVER 2 2 1 Quantum Design Figure 2 1 Block Diagram of Bridge Board Limits and Resolution The user bridge board automatically adjusts the Table 2 2 Current Power and Voltage Limits excitation current of its active channels but you can specify the maximum allowable current power and voltage for each channel see table 2 2 The excitation current is limited by the specified maximum current voltage or power whichever parameter setting limits the excitation current to a lower value PARAMETER VALUES Current Limit 0 01 5000 A 0 001 1000 uW Power Limit 1 95 mV Voltage Limit
38. he names of menus options buttons and panels appearing on the PC monitor or on the Model 6000 PPMS Controller LCD screen The gt symbol indicates that you select multiple nested software options Bold text and all capital letters distinguish the names of keys located on the front panel of the Model 6000 PPMS Controller The Courier font distinguishes characters you enter from the PC keyboard or from the Model 6000 PPMS Controller front panel The Courier font also distinguishes code and the names of files and directories Angle brackets distinguish the names of keys located on the PC keyboard A plus sign connecting the names of two or more keys distinguishes keys you press simultaneously A pointing hand introduces a supplementary note An exclamation point inside an inverted triangle introduces a cautionary note A lightning bolt inside an inverted triangle introduces a warning PPMS Resistivity Option User s Manual Quantum Design C H APTER 1 1 1 1 2 Introduction to the Resistivity Option Introduction This chapter contains the following information e Section 1 2 presents an overview of the e Section 1 3 discusses the Resistivity PPMS Resistivity option option software Overview of the Resistivity Option The Resistivity option for the Physical Property Measurement System PPMS adds a configurable resistance bridge board called the user bridge board to the Model 6000 PPMS Controller None of the four cha
39. he usual procedures described in chapter 3 However there are a few additional considerations for resistance measure ments with the Helium 3 system These considerations are described below 4 3 2 1 RESERVED CHANNEL 3 Channel 3 on the user bridge board is used exclusively for thermometer readback with the Helium 3 system You should never attempt to modify the settings for channel 3 EP For channel 3 you must always select No Action for the Channel Set z parameter in the Resistivity sequence measurement dialog box and the NOTE Scan Excitation sequence measurement dialog box 4 3 2 2 EXCITATION LEVELS The sample mounts provided for mounting samples are constructed of high conductivity copper to provide good thermal anchoring However at temperatures below about 1 K it is normally very difficult to achieve good thermal contact even within the sample itself That is if the excitation current is too high significant self heating of the sample can result in substantial temperature errors where the relevant portions of the sample are warmer than the Helium 3 thermometer reports Again this is not necessarily due to poor contact of the sample to the sample holder it may be due to poor thermal conductance of the sample itself The best way to detect this effect is to repeat measurements using different bridge board excitation levels Itis also generally recommended that you use the smallest possible excitation that still gives an adequate signal
40. ia vil P 4 Conventions in the Manitaal 5 cecestestecisstecdeste hetee op eabes tap eatetsesendde ei e a ris ooa eei i reia iea viii CHAPTER 1 Introduction to the Resistivity Option sese 1 1 Til Introduction eisena e A os a a EEEa e E eatin ES a T ek RSE A 1 1 1 2 Overview of the Resistivity Option sss sese ee eee 1 1 1 2 1 Advantage of Four Wire Resistance Measurements sees eee eee eee 1 2 1 3 Resistivity Option Softwatess sonra a ee ea ra peee eaa ae wate Ata eae anita aa ii 1 2 1 3 1 Activating the Resistivity Software 0 0 ec ee eee 1 2 13 2 Resistivity Control Center sossen este e a labs a ea ethno E EE E EE A bodes E E RE En 1 3 CHAPTER 2 User Bridge Board Operation sss 2 1 EN eie Te nO TTT 2 1 2 2 Function of the User Bridge S TT 2 1 2 2 1 Eimuts and Resolution ressonen ieee ieee AEE ENTRET EE e REAA arama 2 3 2 2 2 Internal Excitation Current Range Selection sse eee ee eee ee eee 2 4 22 3 Calibration ModeS TT 2 4 22 31 Fast Modez si r e E a E E e r E E E E R EES 2 4 2 2 3 2 standard DO s TTT 2 5 2 2 3 3 High Resolution Modeks neire e pri ra ade E r RETETE bide iene 2 5 2 2 4 Div Modes TT E i biked Aiea MR EEE E i a 2 6 2 2 5 Internal Voltage Gaim Contolera teia enora eiaa reai r Er iaaa o EE EEr ano iais a e 2 7 220 Al Converter TTI 2 7 2 3 Changing User Bridge Board Settings sss sees ss eesseeer ereer ennenen nenen nenen 2 8 2 3 1 Using the Bridge Channels Dialog Box to Change Bridge Settings sss 2 9 2 3 2 Using the Bridge Co
41. ing current through the sample regardless of whether a measure ment is being performed Parameter settings for any active channel may be changed immediately by entering or selecting the new values and then selecting the Set button Table 2 6 lists all user definable parameters and identifies the acceptable parameter ranges The Bridge Configuration tab figure 2 4 used to define Resistivity sequence commands also shows the parameter settings for all four user bridge channels However the Bridge Configuration tab indicates a channel is active only if the tab was previously used to activate the channel and like all sequence mode dialog boxes the Bridge Configuration tab does not display status information Parameter settings for any channel activated in the Bridge Configuration tab may be changed in the tab but the new values take effect only when the sequence command is read during a sequence run If the tab is used simply to activate or deactivate a channel the state of the channel changes only when the sequence command is read during the sequence run An approach algorithm allows the initial excitation to exceed the specified power and voltage limits for one fifteenth of a second when the sample resistance is greater than 1 KQ For this reason it is important to estimate the sample resistance before taking measurements and for delicate samples expected to have resistances greater than 1 KQO only a current limit that will not exceed the samples
42. ing the control center to perform all normal system operations is encouraged The Resistivity control center opens as soon as the Resistivity option is activated The control center may be minimized but will not close until the option is deactivated Resistivity Option Bic m Sample Status E Installed Install Remove Samples m Datafile C GdPpms Data NewResData dat View Bridge Setup Measure Figure 1 4 Resistivity Control Center Quantum Design PPMS Resistivity Option User s Manual 1 3 C H APTER 2 User Bridge Board Operation 2 1 2 2 Introduction This chapter contains the following information e Section 2 2 discusses the functionality of e Section 2 4 describes the operation of the the user bridge board user bridge board e Section 2 3 explains how to change the user bridge board settings Function of the User Bridge Board The user bridge board which is the primary hardware component of the PPMS Resistivity option is a nondedicated configurable resistance bridge board The user bridge board is installed behind and accessed through the P1 User Bridge port on the Model 6000 PPMS Controller An electrical cable connects the P1 User Bridge port to the gray ringed Lemo connector on the PPMS probe head and thus connects the user bridge board to the sample installed in the PPMS sample chamber Table 2 1 identifies the electrical conn
43. is set to Off no data can be collected for that channel Use the Data Fields tab to select the system data items you want to save to the data file By default the general system status temperature magnetic field and sample position are selected to be saved The resistivity and excitation read off the active channels are also saved to the file Enter in the Reading Count text box the number of readings you want the system to take and average at each step in the excitation range The readings are averaged regardless of the cali bration mode so if the channel uses high resolution mode see section 2 2 3 3 the operations specific to that mode are performed first before the Resistivity software averages the readings Select OK to add the Scan Excitation command to the sequence Select the Save Sequence File button in the PPMS MultiVu tool bar type a file name for your sequence and then select Save in the pop up dialog box Select the Run Sequence button in the PPMS MultiVu tool bar You saved your new sequence and selected a data file so the sequence should run immediately Status messages in the PPMS MultiVu interface indicate that a sequence is running The commands in the sequence determine the length of time the sequence runs The Scan Excitation command you included in the sequence is executed when it is read during the sequence run PPMS Resistivity Option User s Manual Quantum Design Chapter 3 Section 3 4 Four Wire Resista
44. is associated with one user bridge channel The sample s wD association with a specific channel is identified in the data file header and NOTE cannot be changed in PPMS MultiVu If you change the samples on a puck insert a new puck or wire a sample to some other channel you must create a new data file to ensure that the integrity of the stored data is maintained The Datafile panel in the Resistivity control center see figure 3 2 identifies which Resistivity measurement data file is selected to store the Resistivity measurement data and also maps the file location The panel is blank if a data file has not been selected Selecting the View button in the control center opens the graph view of the currently selected Resistivity data file The Physical Property Measurement System PPMS MultiVu Application User s Manual discusses your options for plotting and viewing data 3 4 1 Creating a Resistivity Data File 1 Select the Browse button in the Resistivity control center The Select a Data File dialog box opens The dialog box lists all existing data files 2 Select the drive and directory where the new data file will reside if necessary The default directory to which PPMS MultiVu writes data files is C OdPpms Data 3 Use the File name text box in the Select a Data File dialog box to enter the name of the new data file Creating a name that helps identify the file as a Resistivity data file is useful If you enter the name of an exi
45. istivity Option User s Manual Quantum Design C H APTER 3 Four Wire Resistance Measurements 3 1 Introduction This chapter contains the following information e Section 3 2 explains how to mount e Section 3 4 discusses the function of samples on Resistivity sample pucks Resistivity data files e Section 3 3 explains how to take four wire resistance measurements 3 2 Sample Mounting Procedures The interface on the Resistivity puck has three groups of four labeled contact pads corresponding to channels 1 through 3 on the user bridge board Each group of contacts has one positive contact and one negative contact for both current and voltage figure 3 1 Up to three samples may be mounted on a conventional Resistivity puck at any given time To mount a sample on a Resistivity puck you position the sample near the center of the puck and use the standard four wire resistivity measurement setup to connect the sample to channel 1 2 or 3 on the user bridge The soft gold plated puck contacts allow leads to be soldered or wire bonded to the user bridge channels After you mount the sample you verify that the sample is making good contact with the puck Each sample is associated with only one user bridge channel and this association is created when you connect the sample to the puck wires read by that channel Figure 3 1 Resistivity
46. ium 3 System sss esse eee eee 4 2 4 31 Measurement Setup TTT 4 2 4 3 1 1 Prepare for the Measurement sese ee eee eee eee 4 2 4 3 1 2 Install the Sample sisii scssecssesisesssssssusssdecsyabap standeseussestsensestess cases sapndesdsssesbeatsopsoadastesvvassssa pessaaseesbese 4 3 4 3 1 3 Start Up the Software spotit rea aine aaea eaa ataa Oee a EESO a SER A SESE EEKE ES RENE aiia REA 4 3 432 Performing Meas tementS s r eesse ec casei copes te od panes sores Ep Aian ene Tee e ia OTEREN EEEE poesves Ap OERSET S E 4 4 4 3 2 B Reserved Channel Brens ret neee aE E E E E EE EEEE AE EE EE ERE 4 4 4 322 Excitation Levels mimea ie e ea a a E a EE E eee eke AR EE AE ERR SE 4 4 43 2 3 Unused Bridge T 4 4 CHAPTER 5 Operation with the Horizontal Rotator sss 5 1 SI Introduction renine R Sa ee eg ine eR N OTTER 5 1 5 2 Overview of Resistivity Operation with the Horizontal Rotator ei ee eee 5 1 5 3 Resistivity Measurements with the Horizontal Romare eee 5 2 5 31 Measurement SetuP e vesscesc05s tesucsecve geet a E by see TdT Rea Tar E age aie 5 2 5 3 1 1 Prepare for the Measurements sci hacen iii eave ith Haga Reh nea ahaa ale Aah os 5 2 5 3 1 Install the Sample isisisi scp dhecestvees Bek tus fees eehececncuaens osebo nE AEE dopa De KEN EEE E EEEE Eaei ayo 5 2 KR e T Up the SoftWare reesti a E a TTT 5 3 5 3 14 Configure the T T 5 3 532 Performing Measurements aoe ai eaa e eee a ea a ate ea ae A Ea ete ede ieee 5 3 5 3 3 T rning Off Br KT 5 3 H PPMS
47. mometers but returns to user bridge channel 1 whenever a resistance is perceived there If the resistance is not that of the calibrated rotator thermometer the temperature controller appears broken so be sure to turn off UserTemp when you are not using the Horizontal Rotator or another customized calibrated thermometer Quantum Design PPMS Resistivity Option User s Manual 5 3 A P PEN Dl XA Installation A l Introduction This appendix contains the following information e Section A 2 explains how to install the user bridge board in the Model 6000 A 2 Installing the User Bridge Board The user bridge board that is part of the PPMS Resistivity option is generally installed at the Quantum Design factory The board can however be easily installed in the field These installation instructions explain how to install the user bridge board in the Model 6000 PPMS Controller The user bridge board installation kit includes the following items One user bridge board part number 3076 050 Four split ring lock washers and 4 40 hex nuts to secure user bridge board to motherboard posts Two jack sockets to secure 25 pin D shell connector to Model 6000 rear panel One 9 1 3 inch 16 wire ribbon cable K KARAK A 2 1 Remove the Model 6000 Cover 1 Take all necessary precautions to protect the user bridge board against static electricity or other electrical damage components inside the Model 6000 Before you touch the user bridge boa
48. n Quantum Design PPMS Resistivity Option User s Manual 2 5 Section 2 2 Chapter 2 Function of the User Bridge Board User Bridge Board Operation Number of Readings Averaged Versus Resistance for Bridge Board Operation in High Resolution Mode dings Read of er mb 3 3 EEE xxx HSAs EEESSS oo o ZSS Aa a gt Onur oe QOO Cex X X XN OW Nn dd oo D 0 6 9 2 O O Qw N tO N LAY lt QE DOI WA OAO GG d GO MO N GNOMO a d we CN d O KO b M o NW N st 0 M oO NW CN st 0 M oO NW N st 0 Resistance ohms Figure 2 2 The number of measurements averaged in high resolution mode varies from 2 to 16 and depends on how far from the base value of 32 767 Q the resistance lies Non integers on the y axis are rounded down in this graph When operating in high resolution mode the user bridge stores any adjustment factors used and reuses them for resistance calculations whenever identical measurement conditions occur on any channel within the next minute This eliminates repetitive measurement of the calibration resistors These adjustment factors are updated after one minute and are erased when an abort is executed when a CAL GPIB command is requested or when the power is turned off 2 2 4 Drive Modes Each active channel on the user bridge board can operate in the AC drive mode
49. n User s Manual Quantum Design Appendix A Installation Quantum Design Section A 2 Installing the User Bridge Board The 25 pin D shell connector fits into the P1 User Bridge port located on the Model 6000 rear panel The four holes in the board fit over the four posts secured on the motherboard Secure the connector P1 User Bridge to the rear panel by inserting the two jack sockets see E in figure A 1 through the connector holes starting from the outer side of the rear panel Secure the user bridge board to the motherboard posts by a placing each washer on a post b placing each nut on a post and then c tightening each nut Connect the four wire ribbon cable from the system bridge board to the socket labeled J5 DRIVER see F in figure A 1 on the user bridge board Connect the 16 wire ribbon cable as follows a Connect one end of the cable to the mother board socket labeled J13 USER BRIDGE see G in figure A 1 b Connect the other end of the cable to the user bridge board socket labeled J1 CONTROL see H in figure A 1 Reinstall the top cover on the Model 6000 by securing it with only the two rear screws see A in figure A 1 Put the top cover back on the console cabinet Press the power button to turn on the Model 6000 The system is now ready for normal use Figure A 1 Model 6000 PPMS Controller with Cover Removed PPMS Resistivity Op
50. nce Measurements Resistivity Data Files 3 4 Resistivity Data Files Resistivity measurement data files store measurement results and other relevant parameters read by the Model 6000 PPMS Controller during resistance measurements The Resistivity software creates Resistivity measurement data files and lets only Resistivity measurement data files be selected to store data from Resistivity measurements Like any PPMS MultiVu measurement data file Resistivity measurement data files have a dat file extension By default the Resistivity software records the following data for every measurement the resistivity and excitation read off each measured user bridge board channel the general PPMS status code and the average system temperature magnetic field and sample position from the measurement The two Resistivity measurement sequence commands allow you to select which PPMS system data items you want to save to the data file The header of each Resistivity data file includes file and sample property information that is defined at the time the data file is created When you create a new file the Resistivity software prompts you to define the sample properties for the sample or samples whose measurement data will be saved to the file Information written to the data file header cannot subsequently be changed in PPMS MultiVu Subsequently changing samples without changing the data files can destroy the validity of the data in the files E Each sample
51. nfiguration Tab to Change Bridge Settings sees sees eee eee eee 2 10 2 3 3 Using the Model 6000 to Change Bridge Settings sss sese eee eee eee 2 11 2 4 Description of User Bridge Board Operation sese sese 2 11 Quantum Design PPMS Resistivity Option User s Manual 1 Contents Table of Contents CHAPTER 3 Four Wire Resistance Measurements seene 3 1 S R Tse ETO T 3 1 3 2 Sample Mounting Procedures TT 3 1 3 3 Taking Four Wire Resistance Measurements sese ee eee ee eee 3 2 3 3 1 Taking Single Point Resistance Measurements see ee eee eee ee eee 3 3 3 3 1 1 Taking Measurements in Immediate Mode sss essen 3 3 3 3 1 2 Taking Measurements in Sequence Mode sss sese 3 4 3 3 2 Taking Multiple Resistance Measurements sees ee ee eee eee 3 6 3 3 2 1 Taking Measurements in Immediate Mode sss essen 3 6 3 3 2 2 Taking Measurements in Sequence Mode uu ee sese 3 7 3A Resistivity Data Files TT 3 9 3 4 1 Creating a Resistivity Data T se rne ee Eren E AEE EE EEEE O EEEE EA ENTE TEE ESEE EEE SES EEE en 3 9 3 4 2 Selecting a Resistivity Data TT 3 10 3 4 3 Adding a Comment to a Resistivity Data Ple sse see 3 11 3 4 4 Changing Resistivity Data Files during a Sequence RUM sss es sees eee eee 3 11 CHAPTER 4 Operation with the Helium 3 System sse 4 1 4 1 Introductions Use Asie aie ieee ma edn dume gina E E Aa E E EAE a auth 4 1 4 2 Overview of Resistivity Operation with the Helium 3 System sees eee ee eee eee 4 1 4 3 Resistivity Measurements with the Hel
52. ng arrangement select another file 6 Select OK to add the Change Datafile command to the sequence file Quantum Design PPMS Resistivity Option User s Manual 3 1 1 Cc HAPTER 4 Operation with the Helium 3 System 4 1 Introduction This chapter contains the following information e Section 4 2 presents an overview of e Section 4 3 describes how to take Resistivity operation with the Helium 3 Resistivity measurements when using system the Helium 3 system 4 2 Overview of Resistivity Operation with the Helium 3 System The Resistivity option may be used with the PPMS Helium 3 Refrigerator System insert Model P825 Use of the Helium 3 insert allows resistance measurements to be performed to below 0 4 K Although samples are mounted differently when the Helium 3 system is being used the operation of the Helium 3 system is otherwise designed to be as transparent as possible The Helium 3 option uses bridge board channel 3 for reading the Helium 3 system thermometer Because the thermometer excitation power must be kept very low below 1 K the enhanced bridge board part number 3076 050 must be used As of July 1999 the enhanced bridge board ships standard with all Resistivity options The new enhanced bridge board has been designed with a precision balanced current source to aid precise readings of large resistances To set up the system for resistance measurements the standard user bridge cable part number 3084 003 is connecte
53. nnels on the user bridge board are dedicated to a specific system operation so all four channels are available to perform four wire resistance measurements on the PPMS The Resistivity option can report resistance as well as resistivity conductance and conductivity Samples for four wire resistance measurements may be mounted on standard PPMS sample pucks see figure 1 2 or on Resistivity sample pucks which are included with the Resistivity option Resistivity sample pucks have four contacts one positive and one negative contact for current and voltage for each user bridge board channel to which a sample may be conventionally wired figure 1 1 Up to three samples may be mounted on a Resistivity puck so the Resistivity option may measure up to three samples at one time Section 3 2 discusses in detail how you mount a sample on a Resistivity puck Figure 1 1 Interface on Resistivity Sample Puck Quantum Design PPMS Resistivity Option User s Manual 1 1 Section 1 3 Chapter 1 Resistivity Option Software Introduction to the Resistivity Option 1 2 1 Advantage of Four Wire Resistance Measurements Using four wires to attach a sample to a sample puck greatly reduces the contribution of the leads and joints to the resistance measurement In a four wire resistance measurement current is passed through a sample via two current leads and two separate voltage leads measur
54. nnot be subsequently changed in PPMS MultiVu 7 Select the units in which you want the measurement results reported for each channel to which a sample is connected The units determine the specific type of data saved for that channel In addition to the resistivity the data file also stores the resistance for each measurement 8 Select OK The data file is created and its name and file location are displayed in the Datafile panel in the Resistivity control center Notice that if you select the Samples button in the Resistivity control center after you create the data file all data entry fields in the File and Sample Properties dialog box are disabled 3 4 2 Selecting a Resistivity Data File 1 Select the Browse button in the Resistivity control center The Select a Data File dialog box opens The dialog box lists all existing data files 2 Double click on the name of a Resistivity data file A warning message pops up if you try to select a file that is incompatible with the Resistivity option As soon as you select a Resistivity data file the File and Sample Properties dialog box opens and displays the information stored in the data file header All data entry fields in the dialog box are disabled 3 Review the information in the File and Sample Properties dialog box to determine whether you have selected the correct data file for your sample If the file stores data for some other sample or for some other sample wiring arrangement r
55. o the sample chamber and select the data file see section 3 3 you can run a sequence that includes the Resistivity command A Resistivity data file must be selected in order to run a sequence that includes the Resistivity or Scan Excitation command Complete the following steps to take a resistance measurement in sequence mode You should refer to the Physical Property Measurement System PPMS MultiVu Application User s Manual for a detailed discussion of sequence operation 1 Select the New Sequence File button in the PPMS MultiVu tool bar A new sequence file is created The sequence command bar also opens 2 Select the Resistivity command in the Measurement Commands group that is in the sequence command bar The Resistivity dialog box opens and displays the Bridge Configuration tab Bridge Configuration Data Fields Channel Current Limit Power Limit Voltage Limit Calibration Drive Set ud uw mv Mode Mode t fon Sim fo fo stenda Sl 2 2 On K han hp hp o Standard 2 Jac 2 4 No Action fo hr fo Standard yY Jac Figure 3 4 Bridge Configuration Tab in Resistivity Dialog Box 3 Use the Channel Set pull down menu in the Bridge Configuration tab to activate the user bridge channels you want to read Any number of channels may be read You may use the No Action option to prevent the channel state from being altered when the command is executed 4 Change the settings of the active user bridge channels as necessary Se
56. on command in the Measurement Commands group that is in the sequence command bar The Scan Excitation dialog box opens and displays the Scan Setup tab Scan Excitation xi Scan Setup Bridge Configuration Data Fields F Excitation Channel Initial Final Delta Spacing Number of Steps k Figure 3 7 Scan Setup Tab in Scan Excitation Dialog Box Quantum Design PPMS Resistivity Option User s Manual 3 7 Section 3 3 Chapter 3 Taking Four Wire Resistance Measurements Four Wire Resistance Measurements 3 8 10 Use the Scan Setup tab to define the excitation range and the mode of spacing the steps within the excitation range See section 3 3 2 1 for an explanation of the Scan Excitation parameters Use the Channel Set pull down menu in the Bridge Configuration tab to activate the user bridge channels you want to read Any number of channels may be read You may use the No Action option to prevent the channel state from being altered when the command is executed Change the settings of the active user bridge channels as necessary Section 2 3 explains how you change user bridge settings When you use the Scan Excitation sequence command to activate user bridge channels the resistivity and excitation read off the activated channels are saved to the data file and the data items for the activated channels are automatically selected in the Data Fields tab see figure 3 5 When a user bridge channel is deactivated that
57. or the DC drive mode AC mode is the default drive mode In AC mode the user bridge board applies a DC excitation to the sample and reads the potential drop across the sample Then the user bridge board reverses the current and reads the potential drop again The user bridge averages the absolute value of the positive and negative voltage readings The AC excitation which is a square wave excitation is synchronized to the AC line frequency of 50 or 60 Hz in order to reject AC line noise Operation in AC mode eliminates errors from DC offset voltages and produces the most accurate readings A symbol appearing on the Model 6000 front panel display designates AC mode In DC mode the user bridge board averages two consecutive voltage readings that have the identical polarity DC mode produces less accurate voltage readings than AC mode but is a useful mode of operation when reversing polarity would significantly affect the sample Due to the averaging in DC mode the effective measurement rate is also 7 5 or 8 3 Hz 2 6 PPMS Resistivity Option User s Manual Quantum Design Chapter 2 User Bridge Board Operation 2 2 5 Section 2 2 Function of the User Bridge Board Both AC and DC measurements are synchronized with the power line frequency If you are working in a 50 Hz environment instead of a 60 Hz environment the user bridge board measures at 8 33 Hz rather than 7 5 Hz Measurement rates are also synchronized if the power line fre
58. ple position used during the measurement Resistivity and excitation are reported in the measurement units that were specified when the data file was created for the measured channels Values of zero excita tion and zero resistivity are reported for those channels to which no sample is wired PPMS Resistivity Option User s Manual 3 3 Section 3 3 Chapter 3 Taking Four Wire Resistance Measurements Four Wire Resistance Measurements 3 4 6 Select the Save button in the Resistivity Quick Measure dialog if you want to save the measure ment results to the specified data file You must select Save in order to save the data The Save button is disabled after you select it and it remains disabled until another single point resistance measurement runs The button is also disabled if a data file has not been selected 7 Select Close if you want to close the Resistivity Quick Measure dialog box If you saved the measurement data you may find it useful to examine the data Clicking on the View button in the Resistivity control center opens the graph view of the selected data file Once the graph view is open you may select many different graph formats to plot the data or you may select various other data viewing formats The Physical Property Measurement System PPMS MultiVu Application User s Manual discusses data viewing formats and graph formats in detail 3 3 1 2 TAKING MEASUREMENTS IN SEQUENCE MODE After you insert the sample int
59. polarities for AC mode and the resistance is reported according to one of the three calibration modes Enabled channels are scanned sequentially and then necessary calibration channels are read In standard mode the resistance is not reported until the appropriate calibration resistor has been measured if this is possible When a channel is in high resolution mode other channels continue to operate as usual but a resistance is reported for only the high resolution channel after an appropriate number of readings has been recorded and averaged The user bridge board has one current source and voltage detector Consequently measurements do not actually occur simultaneously although the measurements occur so close to each other you really will not notice that they are not simultaneous On a normal PPMS configured for measurements on three user bridge channels the first channel measured is 1 and the last channel measured is 3 An active user bridge board channel is always running and passing current through the sample regardless of whether a measurement is being performed Allowable Measurement Parameters ual Measurement Parameters Absolute Current Limit 0 1 2 3 dl 5 mA Figure 2 5 The allowed measurement parameters V and are constrained by the user specified voltage limit Vmax Current limit Imax and power Pmax This plot shows Vmax 82 MV Imax 4 2 MA and Pmax 0 2 mW 2 12 PPMS Res
60. quency is between 45 and 70 Hz Internal Voltage Gain Control The user bridge board performs voltage gain control internally Because the gain affects measurement resolution an understanding of the gain control is useful All voltage readings are first multiplied by a factor of 25 Automatic gain control further adjusts the gain according to the measurement conditions The gain is decreased when the A D converter reads a voltage greater than or equal to 90 of full scale The gain is increased when the A D converter reads a voltage less than 9 5 of full scale If the measured voltage falls in a zone between two gain settings or below 9 5 of full scale on the highest setting the gain is not adjusted The A D resolution is determined by the following equation Like the excitation DAC the 20 bit A D converter uses one bit to designate sign Full Scale A D Resolution 9 2 Table 2 5 summarizes the gain settings Table 2 5 Voltage Gain Settings FULL MAXIMUM MINIMUM A D GAIN SCALE VOLTAGE VOLTAGE RESOLUTION xl 100 0 mV 92 0 mV 9 50 mV 190 70 nV x10 10 0 mV 9 0 mV 0 95 mV 19 07 nV x25 4 0 mV 3 6 mV 0 38 mV 7 63 nV x50 2 0 mV 1 8 mV 3 81 nV 2 2 6 A D Converter Calibration Like other A D converters in the Model 6000 the user bridge board s A D converter undergoes self calibration upon power up A D converter calibration can be invoked at any time with a CAL remote GPIB command and calibr
61. ration 2 2 2 Internal Excitation Current Range Selection The excitation current range selection for the user bridge board Table 2 3 Current Ranges is performed internally However it is useful to understand the range selection process Table 2 3 lists the four excitation MAXIMUM STEP current ranges and the corresponding step sizes CURRENT SIZE The bridge board uses the range resulting in the smallest step 5 0 mA 2 44 uA size while still providing the necessary current For display 0 5 mA 244 00 nA purposes the excitation current is rounded to the nearest step value 50 0 pA 24 40 nA Step size is calculated by 5 0 uA 2 44 nA Max Current Step Size zii because the excitation DAC is 11 bits bit 12 designates the current s sign 2 2 3 Calibration Modes Each active channel on the user bridge board can operate in the fast standard or high resolution calibration mode The letter F S or H is displayed on the Model 6000 front panel to indicate the mode to which each channel is set Standard mode is the default calibration mode Table 2 4 Function and Suggested Use of Calibration Modes MODE DEFINITION USAGE Fast Last measured current and voltage are read to e For resistance measurements calculate resistance Then resistance is reported that are part of control loop without adjusting reading requiring quick feedback e To take fastest measurements e To view noise in signals
62. rd or any other component inside the Model 6000 ground yourself by touching the metal back or metal side panel of the Model 6000 case In addition limit your movement during installation and whenever you handle the user bridge board movement increases the possibility of static discharge WV Static discharge can damage components on the user bridge board and other CAUTION Quantum Design PPMS Resistivity Option User s Manual A 1 Section A 2 Installing the User Bridge Board A 2 2 YV CAUTION V CAUTION Appendix A Installation 2 Set the system magnetic field to zero and wait for the field to reach zero 3 Select CTRL gt 1 Interactive Control gt 8 Shutdown Mode from the Model 6000 front panel The PPMS enters shutdown mode 4 Use the switch on the front panel of the Model 6000 to turn off the Model 6000 Do not turn off the vacuum pump or any other electronics in the PPMS electronics cabinet 5 Clear the top of the PPMS console cabinet and then remove the top cover of the console cabinet by lifting it up and off the console 6 Remove the top cover from the Model 6000 as follows If only the two rear top cover screws see A in figure A 1 secure the top cover remove these screws and then remove the top cover e If the two rear top cover screws see A in figure A 1 and the two front top cover screws see B in figure A 1 secure the top cover do the following a b c d
63. sample puck with three samples mounted for four wire resistance measurements Quantum Design PPMS Resistivity Option User s Manual 3 1 Section 3 3 Chapter 3 Taking Four Wire Resistance Measurements Four Wire Resistance Measurements 3 3 YV CAUTION E NOTE 3 2 The Resistivity puck does not include contacts for user bridge channel 4 because channel 4 is not prewired for sample measurements The 12 pins at the bottom of the PPMS sample chamber allow three samples to be measured four pins are required to measure one sample Consequently user bridge channels 1 through 3 normally take measurements The Resistivity option may also be used with standard PPMS sample pucks When you use the standard sample puck refer to table 2 1 to determine the correct wiring Taking Four Wire Resistance Measurements Resistance can be measured once or it can automatically be measured with a number of excitation currents in a given excitation current range The Resistivity command takes one resistance measure ment The Scan Excitation command takes measurements throughout a specified excitation range Resistivity and Scan Excitation can be executed immediately or included in a PPMS MultiVu sequence file An approach algorithm allows the initial excitation to exceed the specified power and voltage limits for one fifteenth of a second when the sample resistance is greater than 1 KQ For this reason it is important to estimate the sample resist
64. sary Specifying a current limit of zero for any channel deactivates the channel Table 2 6 identifies the acceptable parameter ranges 4 Set the power limit for each channel as necessary Specifying a power limit of zero for any channel deactivates the channel 5 Set the voltage limit for each channel as necessary Select the calibration mode the channel uses to measure sample resistance The standard fast and high resolution modes are available Section 2 2 3 discusses the calibration modes in detail Table 2 4 suggests possible uses for each mode 2 10 PPMS Resistivity Option User s Manual Quantum Design Chapter 2 Section 2 4 User Bridge Board Operation Description of User Bridge Board Operation 7 Select the drive mode the channel uses during the resistance measurement The AC and DC drive modes are available You are advised to use AC mode unless reversing polarity would significantly affect the sample Section 2 2 4 discusses the drive modes in detail 8 Select the other tab or tabs in the dialog box and finish defining the measurement if necessary Refer to sections 3 3 1 2 and 3 3 2 2 9 Select OK The Resistivity or Scan Excitation command is added to the selected sequence file The new parameter settings go into effect when the command is read while the sequence runs 2 3 3 Using the Model 6000 to Change Bridge Settings You may also use the Model 6000 Setup Bridge Channel screen to change user bridge board settings
65. sting file that file will be overwritten 4 Select Open The File and Sample Properties dialog box opens figure 3 8 and all data entry fields in the dialog box are enabled Quantum Design PPMS Resistivity Option User s Manual 3 9 Section 3 4 Chapter 3 Resistivity Data Files Four Wire Resistance Measurements File and Sample Properties xi r Data File Title ss Resistivity Measurement Data p Sample Description a Channel Name Area mn Length mm Units 1 Example Sample fi fi Ohm m Y Figure 3 8 File and Sample Properties Dialog Box 5 Use the Data File Title text box in the File and Sample Properties dialog to specify a title for the graph view of the data file if you like Specifying a title for the graph view is not mandatory 6 Enter in the Sample Description text boxes representing the user bridge channel or channels to which the installed sample or samples are connected the following information a The name ora description of each sample b The area in mm of each sample Use 1 if you are uncertain what the area of the sample is A value of will not affect the data c The length in mm of each sample Use 1 if you are uncertain what the length of the sample is A value of 1 will not affect the data The information you enter in the File and Sample Properties dialog box is saved to the data file header Enter the information carefully it ca
66. the sample chamber and select the data file see section 3 3 you can run a sequence that includes the Scan Excitation command A Resistivity data file must be selected in order to run a sequence that includes the Resistivity or Scan Excitation command The Scan Excitation sequence command functions similarly to other PPMS MultiVu scan commands When the system reads Scan Excitation in a running sequence it takes measurements on all active user bridge channels throughout the entire excitation range before executing the next command in the sequence Scan Excitation thus simplifies the process of scanning through an excitation range and by reducing the number of commands in a sequence Scan Excitation helps prevent the sequence file from getting too large However Scan Excitation unlike other scan commands creates a one line control loop into which no additional commands may be inserted Refer to the Physical Property Measurement System PPMS MultiVu Application User s Manual for a detailed discussion of scan commands and control loop operation Complete the following steps to take multiple resistance measurements in sequence mode You should refer to the Physical Property Measurement System PPMS MultiVu Application User s Manual for a detailed discussion of sequence operation 1 Select the New Sequence File button in the PPMS MultiVu tool bar A new sequence file is created The sequence command bar also opens 2 Select the Scan Excitati
67. tion User s Manual A 3 References Quantum Design 1998 Physical Property Measurement System Hardware Manual 1999 Physical Property Measurement System Helium 3 Refrigerator System User s Manual 1998 Physical Property Measurement System Horizontal Rotator Option User s Manual 1998 Physical Property Measurement System PPMS MultiVu Application User s Manual PPMS Resistivity Option User s Manual References 1 Quantum Design Index AC mode applying excitation current to sample 2 6 See also User bridge board Operation as default drive mode 2 6 recommended use of 2 10 2 11 synchronized with power line frequency 2 7 as user bridge board parameter 2 6 2 8 A D converter on user bridge board calibrating 2 7 DC mode applying excitation current to sample 2 6 See also User bridge board Operation synchronized with power line frequency 2 7 as user bridge board parameter 2 6 2 8 Calibration modes as user bridge board parameter 2 4 2 8 See also Fast mode High resolution mode Standard mode Current limit for user bridge board 2 3 2 8 Drive modes 2 6 2 7 2 8 Enhanced bridge board 4 1 Excitation current ranges 2 4 Fast mode calculating sample resistance in 2 4 suggested usage 2 4 as user bridge board parameter 2 4 2 8 Four wire resistance measurements advantage of 1 2 extending temperature range of See Helium 3 Refrigerator System option rotating samples
68. tions panel and then select Activate Option Manager Ea Available Options Active Options Activate gt gt lt lt Deactivate Close Figure 1 3 Option Manager Dialog Box 1 2 PPMS Resistivity Option User s Manual Quantum Design Chapter 1 Section 1 3 Introduction to the Resistivity Option Resistivity Option Software 1 3 2 Note that only one measurement option may be active at a time An error message pops up if you attempt to activate a second measurement option If you need to deactivate an option select it in the Active Options panel that is in the Option Manager dialog box and then select Deactivate As soon as you activate the Resistivity option the Resistivity control center opens and the Measure menu items and measurement sequence commands that are specific to the Resistivity option appear in the PPMS MultiVu interface Resistivity Control Center The Resistivity control center makes basic system operations such as installing samples selecting or creating data files and setting up and running immediate mode resistance measurements more natural and convenient Automated routines initiated with control center commands prompt you to complete the necessary actions to install samples or create data files Clearly labeled data fields indicate whether a sample is installed in the PPMS sample chamber or identify which measurement data file if any is selected to store Resistivity measurement data Us
69. to noise ratio 4 3 2 3 UNUSED BRIDGE CHANNELS Due to the extremely low excitation currents used for reading the thermometer on channel 3 there can be significant cross talk from the other bridge channels under certain conditions In the worst case this can produce instabilities in the temperature control The worst case cross talk appears when unused bridge channels are not explicitly turned off In this case the current drive multiplexer can create unwanted voltage spikes when switching from an open load to a neighboring channel Therefore always turn off unused bridge channels 4 4 PPMS Resistivity Option User s Manual Quantum Design C H APTER 5 5 1 5 2 Operation with the Horizontal Rotator e Introduction This chapter contains the following information e Section 5 2 presents an overview of e Section 5 3 describes how to take Resistivity operation with the Horizontal Resistivity measurements when using Rotator the Horizontal Rotator Overview of Resistivity Operation with the Horizontal Rotator The Resistivity option may be used with the PPMS Horizontal Rotator option Model P310 Use of the Horizontal Rotator allows the sample to be rotated around an axis perpendicular to the magnetic field of a longitudinal PPMS magnet The Horizontal Rotator option uses bridge board channel for reading the thermometer on the rotator Consequently once channel is configured its settings must not be changed Only channels 2 an
70. to the gray color coded port on the probe head Plug the 25 pin connector labeled P1 User Bridge into the P1 User Bridge port on the rear of the Model 6000 E RESISTIVITY Es 3084 003 T Ji P1 1 Q REV_B USER BRIDGE Figure 4 1 User Bridge Cable 4 2 PPMS Resistivity Option User s Manual Quantum Design Chapter 4 Section 4 3 Operation with the Helium 3 System Resistivity Measurements with the Helium 3 System 4 3 1 2 INSTALL THE SAMPLE 1 Mount the sample on a Helium 3 sample mount part number 4092 610 Note that at temperatures below 1 K intimate thermal contact between the sample and the copper holder is very important to reduce temperature errors A thin film of Apiezon N Grease works well to aid thermal contact Apiezon N Grease is supplied with the Model P825 Helium 3 insert Refer to figure 4 2 below to wire the sample to the stage The plug in sample mount is clearly labeled for mounting two samples Co PLO P al Figure 4 2 Helium 3 sample puck with two samples mounted for four wire resistance measurements Attach the plug in sample stage to the Helium 3 refrigerator probe Refer to the Physical Property Measurement System Helium 3 Refrigerator System User s Manual for detailed instructions Insert the Helium 3 refrigerator probe into the sample chamber Refer to the Physical Property Measurement System Helium 3 Refrigerator System User s Manual for detailed ins
71. tructions 4 3 1 3 START UP THE SOFTWARE Quantum Design Start up PPMS MultiVu if the application is not running Activate the Helium 3 option in PPMS MultiVu Do the following a select Utilities gt Activate Option b click on Helium3 under the Available Options heading and then c select the Activate button Activate the Resistivity option in PPMS MultiVu Do the following a select Utilities gt Activate Option b click on Resistivity under the Available Options heading and then c select the Activate button Both the Helium 3 software and Resistivity software must be running before you can initiate a measurement Initiate a Helium 3 system test by using PPMS MultiVu or the Model 6000 front panel to set an initial temperature for example 300 K The Helium 3 temperature control is activated on the first Temperature Set command The software checks out the Helium 3 system downloads any necessary configuration data to the Model 6000 console and begins controlling temperature PPMS Resistivity Option User s Manual 4 3 Section 4 3 Chapter 4 Resistivity Measurements with the Helium 3 System Operation with the Helium 3 System 4 3 2 Performing Measurements Once the Helium 3 refrigerator probe is inserted in the sample chamber and the Helium 3 and Resistivity software applications are running you may take resistance measurements at temperatures as low as 0 4 K You take measurements and write sequences according to t
72. ure excitation step size is adjusted Dialog Box Use the Final text box to specify the final current in the excitation range Change the value of Delta if necessary If you change Delta the Steps value is adjusted Use the Steps text box to specify the number of different excitation currents at which measure ments are read in the excitation range Specifying the number of steps is not mandatory If you change the number of steps the Delta value is adjusted Use the Spacing pull down menu to select the mode of spacing the steps Linear mode which is the default evenly spaces the steps Logarithmic mode logarithmically spaces the steps Power mode separates the steps by i Enter in the Readings text box the number of readings you want the system to take and average at each step in the excitation range The readings are averaged regardless of the calibration mode so if the channel uses high resolution mode see section 2 2 3 3 the operations specific to that mode are performed first before the Resistivity software averages the readings Select the Bridge Setup button if you want to review or change user bridge settings A channel must be active to be measured Section 2 3 explains how you change user bridge settings Select Measure The measurement begins The Measure button reads Cancel during the mea surement You select Cancel to abort the measurement As soon as the measurement is complete the Scan Excitation Quick

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