GMR SETUP
AMIT NATH (amitnath@iitk.ac.in)
(ALL MANUALS ARE IN THE DRAWER MARKED “KEITHLEY”)
1) Keithley1 (Dipti):
i)
6517A Electrometer/High Resistance Meter (Asha, Sanjeev, Sista, Hare)
ii)
7001 Switch System
iii)
7065 Hall Effect Card
iv)
2182 Nano-Voltmeter
v)
220 Programmable Current Source (Sista, Hare)
vi)
6167 Guarded Adapter
vii)
237-ALG-2 3-Lug Triax to Individual Leads: I No.
viii)
6011 Triax to Individual Leads: 1 No.
ix)
7024-10 Triax to Triax: 1 No.
x)
7025-10 Triax to Triax: 4 Nos.
xi)
7078-TRX-10 Triax to BNC: 1 No.
xii)
IEEE-488 GPIB Cables: 5 Nos.
xiii)
CEC 488 Interface Card2
2) Lakeshore3 (Dipti):
i)
662 Electromagnet and Power Supply
ii)
450 Gaussmeter
iii)
331 Temperature Controller
3) Scientific Equipment and Services, Roorkee4 (Asha, Dipti, Hare, Sanjeev):
i)
DFP-02 Four Point Probe Setup
1.
K. C. Shashikumar, kcshashi@keithley.com, www.keithley.com; Rohit Sood,
rsood@keithley.com, 9811064680
2.
info@cec488.com, www.cec488.com
3.
J. P. Baughman, sysservice@lakeshore.com, Lakeshore Cryotronics, Inc., www.lakeshore.com
4.
info@sestechno.com, www.sestechno.com/pro1/contact.htm
INSTRUCTIONS FOR USING LAKESHORE 662 POWER SUPPLY
1. Make sure that the WATER INPUT and WATER OUTPUT from pump are
OK.
2. Switch ON pump.
3. Check the Power Switch (OFF position) at the back cover of the
Lakeshore power supply.
4. Check if the “Stand-By” switch is in the lower (0) position on the front
panel of the Lakeshore Power Supply.
5. Check if the two ten-turn potentiometers are indicating 0 on the front
panel of the Lakeshore Power Supply.
6. Switch ON the three-phase mains power supply.
7. Check the output on each of the phases on each of the phase voltmeters
of the CVT.
8. In case the voltage outputs are different on the phase voltmeters of the
CVT, change each of them to 220 V using the RAISE and LOWER push
buttons on each of the phases of the CVT.
9. Switch ON the Power Switch at the back cover of the Lakeshore 662
Power Supply. The green indicator “Mains Connected” lights up on the
front panel.
10. Switch the “Stand-By” switch to the Upper Position: the four green LEDs
light up.
11. Select the polarity with the “polarity” locking lever switch (pull the
lever while switching).
12. Press the green “Power On” push button to start the current supply to
the magnet. The green power indicator lights up.
13. Turn the two ten-turn potentiometers to adjust the output current. The
output voltage and output current are displayed.
14. Press the “off” push button to stop the output current. The “power”
indicator lights off.
15. Keep the water pump running for at least an hour.
16. Switch the “Stand-By” switch to 0 to completely power down the supply.
All the indicators switch off after some time.
17. Turn the Power Switch to OFF position (at the back cover of Power
Supply).
18. Switch OFF the three-phase MAINS power supply.
19. Switch off the water pump.
EMERGENCY RESPONSE FOR LAKESHORE 662 POWER SUPPLY
(e.g., POWER FAILURE)
1. Switch OFF the power switch at the back cover of the Lakeshore power
supply.
2. Switch OFF the three-phase MAINS power supply.
3. Switch off the water pump.
4. Connect the water supply to the tap water supply and let the water run
for at least one hour through the Lakeshore system.
EMERGENCY RESPONSE FOR K6517A, K2182, K7001, K220, L450
1. Switch off the POWER buttons on each of the instruments.
2. Switch off CVT1 and CVT2.
3. Switch off the power supply to the CVT.
INSTRUCTIONS FOR MEASURING GMR
(MANUAL)
1. Power ON CVT and the Keithleys, Lakeshore 450 Gaussmeter and
Lakeshore 662 Electromagnet Power Supply.
2. Connect the OUTPUT COMMON and GROUND at the back of K6517A
Electrometer and K220 Current Source.
3. Secure the sample holder and the connectors.
4. Configure and use the K200 Current Source as:
a. Enter the V-limit
b. Enter the Current Source value. Refrain from using negative
values. Use the switch system instead to reverse the polarity.
c. Use the “OUTPUT OPERATE” to toggle between the OUTPUT ON
and OUTPUT OFF modes.
5. Configure the K2182 Nano-Voltmeter as:
a. Select the Auto-Range mode by pressing the “AUTO” button.
6. Configure and use the K6517A Electrometer as:
a. Select the Current Mode by pressing the “I” button.
b. Select the lowest measurement range by pressing the “∇” button
below the “AUTO” button.
c. Zero correct the ammeter by pressing “REL” button.
d. Select the Auto-Range mode by pressing the “AUTO” button.
e. Press “Z-CHK” to go into the current measurement mode.
f. After completing measurements, press “Z-CHK” again before
switching off the instrument.
7. Use the K7001 Switch System as:
a. Enter the cross-point matrix as given in page 3-5 in the manual of
K7065 Hall Effect Card. Enter the Rows as Columns and vice
versa. For e.g., the cross-point matrix for V1 is given as:
1,2
2,1
3,3
4,4
which should be entered as:
1 ENTER 2 ENTER 1 ENTER 1 ENTER 1 ENTER 2 ENTER 1 ENTER 3
ENTER 3 ENTER 1 ENTER 4 ENTER 4 ENTER 1 ENTER 4 ENTER 5
ENTER
which is displayed as:
1!2!1, 1!1!2, 1!3!3, 1!4!4, 1!4!5,
The fifth set is to close the cross-points for guarding.
b. Press “CLOSE” to close the cross-points.
c. After the measurements, press “OPEN ALL” to open all the crosspoints.
d. Press “CLEAR LIST’ to clear the cross-point list.
e. Repeat the steps (a) through (d) for the next set of cross-points.
8. Use the L450 Gauss-meter as:
a. Position the field probe as close to the sample as possible with
the “LAKESHORE” logo towards the north pole of the
electromagnet.
b. The display will show the magnetic field at the probe tip.
INSTRUCTIONS FOR MEASUREING GMR
(PC INTERFACE CONTROLLED)
1. Power on all the Keithleys, Gauss-meter and the Electromagnet Power
Supply.
2. Secure the sample holder and the connectors.
3. Run command.com and run the appropriate .EXE file from the
C:\WINDOWS\Profiles\Deepak\Desktop\PROGRAMS directory. The
summary of the .EXE files is given below:
a. MRA.EXE
-
Measure GMR in A configuration.
b. MRB.EXE
-
Measure GMR in B configuration.
c. MRC.EXE
-
Measure GMR in C configuration.
d. MRBC.EXE
-
Measure GMR in BC configuration.
e. MRD.EXE
-
Measure GMR in D configuration.
f. MRE.EXE
-
Measure GMR in E configuration.
g. MRF.EXE
-
Measure GMR in F configuration.
h. MR_IV.EXE
-
Take V(dependent)-I plots.
i. MR_TIME.EXE
-
Measure transient GMR voltages.
4. Enter the “Sample Identity”, “Sample Thickness,” and “Current Source”
as prompted in each program. Do not enter a “SPACE” character when
entering strings. Change the current supplied to the electromagnet from
the Lakeshore 662 panel as and when prompted by the program.
5. The output is automatically saved in a corresponding sub-directory of
C:\WINDOWS\Profiles\Deepak\Desktop\PROGRAMS\OUTPUT. The
filenames are indicated both at the start and the end of each program.
For e.g., the two output files of MRA.EXE will be saved as
…\DESKTOP\PROGRAMS\OUTPUT\MRA\MRA1~1.LOG and
…\DESKTOP\PROGRAMS\OUTPUT\MRA\MRA2~1.LOG. The number after
the ‘~’ character increments next time MRA.EXE is run. The output will
be saved in MRA1~2.LOG and MRA2~2.LOG in the second run.
6. After the experiment, exit the program and switch off all the
instruments. Take care to keep the water supply running through the
electromagnet power supply for at least an hour.
INTRUCTIONS FOR MEASURING HALL EFFECT
(MANUAL)
1. Power ON CVT and the Keithleys, Lakeshore 450 Gaussmeter and
Lakeshore 662 Electromagnet Power Supply.
2. Connect the OUTPUT COMMON and GROUND at the back of K6517A
Electrometer and K220 Current Source.
3. Secure the sample holder and the connectors.
4. Configure and use the K200 Current Source as:
a. Enter the V-limit
b. Enter the Current Source value. Refrain from using negative
values. Use the switch system instead to reverse the polarity.
c. Use the “OUTPUT OPERATE” to toggle between the OUTPUT ON
and OUTPUT OFF modes.
5. Configure the K2182 Nano-Voltmeter as:
a. Select the Auto-Range mode by pressing the “AUTO” button.
6. Configure and use the K6517A Electrometer as:
a. Select the Current Mode by pressing the “I” button.
b. Select the lowest measurement range by pressing the “∇” button
below the “AUTO” button.
c. Zero correct the ammeter by pressing “REL” button.
d. Select the Auto-Range mode by pressing the “AUTO” button.
e. Press “Z-CHK” to go into the current measurement mode.
f. After completing measurements, press “Z-CHK” again before
switching off the instrument.
7. Use the K7001 Switch System as:
a. Enter the cross-point matrix as given in page 3-8 in the manual of
K7065 Hall Effect Card. Enter the Rows as Columns and vice
versa. For e.g., the cross-point matrix for V1 is given as:
2,1
1,3
3,4
4,2
which should be entered as:
1 ENTER 1 ENTER 2 ENTER 1 ENTER 3 ENTER 1 ENTER 1 ENTER 4
ENTER 3 ENTER 1 ENTER 2 ENTER 4 ENTER 1 ENTER 4 ENTER 5
ENTER
which is displayed as:
1!1!2, 1!3!1, 1!4!3, 1!2!4, 1!4!5,
The fifth set is to close the cross-points for guarding.
b. Press “CLOSE” to close the cross-points.
c. After the measurements, press “OPEN ALL” to open all the crosspoints.
d. Press “CLEAR LIST’ to clear the cross-point list.
e. Repeat the steps (a) through (d) and/or change the
electromagnet field polarity for the next set of cross-points.
8. Use the L450 Gauss-meter as:
a. Position the field probe as close to the sample as possible with
the “LAKESHORE” logo towards the north pole of the
electromagnet.
b. The display will show the magnetic field at the probe tip.
INSTRUCTIONS FOR MEASURING HALL EFFECT
(PC INTERFACE CONTROLLED)
1. Power on all the Keithleys, Gauss-meter and the Electromagnet Power
Supply.
2. Secure the sample holder and the connectors.
3. Manually apply a desired magnetic field.
4. Run command.com and run HALL.EXE file from the
C:\WINDOWS\Profiles\Deepak\Desktop\PROGRAMS directory.
5. Enter the “Sample Identity”, “Sample Thickness,” and “Current Source”
as prompted in each program. Do not enter a “SPACE” character when
entering strings.
6. The output is automatically saved in
C:\WINDOWS\Profiles\Deepak\Desktop\PROGRAMS\OUTPUT\HALL\. The
filenames are indicated both at the start and the end of each program.
For e.g., the output file of HALL.EXE will be saved as
…\DESKTOP\PROGRAMS\OUTPUT\HALL\HALL~1.LOG. The number after
the ‘~’ character increments next time HALL.EXE is run. The output will
be saved in HALL~2.LOG in the second run.
7. After the experiment, exit the program and switch off all the
instruments. Take care to keep the water supply running through the
electromagnet power supply for at least an hour.
THINGS TO DO
1. Keep all the Keithley and the Lakeshore equipments in boxes.
2. Arrange a hanger for all the cables.
3. Make a sample holder for GMR measurements.
4. Connect the water chiller to the water pump.
5. Add a water filter to the water intake of the pump.
6. Interface the Lakeshore 662 Power Supply through the Lakeshore 450
Gaussmeter.
7. Make T-connections (with two 3-way valves or four 2-way valves) for
running both chilled water and tap water through the Electromagnet
Power Supply.