Thu 17 Sept 2009

First angle calibration using Hall effect

- Field held at 0.2 T, measured V_H and I at various angles. Fridge at 4K.

Hall res plotted v rotator angle readout
parallel to field =~ 138 deg

perpendicular to field =~ 226 deg

delta theta = 88 deg (scaling factor --> may be due to error in controller readout due to high resistance of Mn wires)

  • Rotator angle callibration using hall effect: (black line = sine curve fit)

  • Hall effect angle callibration offset so 0 deg = parallel, and Hall resistance in Ohms:
Nice graph; Suggestion -use jpgs, not bmp if possible.-- AlexHamilton - 17 Sep 2009

Fri 18 Sept 2009

Fridge cooled to base by Oleh.

Ashwin did measurements at different tilt angles, using 10nA constant current.


  • SdH data 1T: 140 deg and 138 deg:


  • Rotator was operated in active feedback mode so angle was held constant (otherwise rotator drifts)
  • All runs were done at MC temp ~100mK
  • Rotator static voltage was kept at V0 = 0.5V
  • Field was swept at 0.2T/min (too fast?) up to 1 T
  • All data can be found in: N:/Ashwin/Hall Effect Laphangs Sample/18-9-09 1T SdH runs

Mon 21 Sep 2009

  • Theta measured from Hall effect (sin-1 Rmax/R) vs Theta set:
  • got slope of 1.02 for uncorrected data as expected...
  • The correction was made by assuming series resistance of 215 ohms (due to Mn wiring) in each of the 3 sensing lines. This results in a slope of 1.004...
-- AshwinSrinivasan - 21 Sep 2009

Wed 23 sep 2009

  • drift_with_time.PNG

No active feedback here either

Thurs 24 Sep 2009

QHE at 8T:

Rxy at different angles is plotted vs perpendicular B

(except first trace at 138 deg - because Bperp ~ 0)



Hall resistance v B at different angles:

( For the Hall data above, I suspect that the perpendicular trace was taken at a much lower temperature, or without active feedback, or both? Because the spin split plateaus are actually clearest there. Aswin? -- AlexHamilton - 29 Sep 2009 )'re right, there was no active feedback for the last perp trace, so the temp was probably ~40mK. For the other traces active feedback was on, T ~90mK

-- AshwinSrinivasan - 29 Sep 2009

Hmm. That means one should not put the two datasets in the same graph without making it clear that they are at different temperatures. It makes it harder to show that the oncreasing in-plane field is strengthening the spin splitting.

It would be interesting to go back to this sample one day and figure out what the electron temperature is with and without active feedback on. -- AlexHamilton - 29 Sep 2009

Fri 25 Sep 2009

Hall effect used for angle callibration again, this time done with labview:


according the the above fit:

parallel = 138.1, perpendicular = 225.5

delta Theta = 87.5 deg


According to this fit, parallel = ~138.3

-- AshwinSrinivasan - 25 Sep 2009

Updates on angle calibration and drift

See AttocubeMoreRotatorTestingForRSI for updates on the angle calibration and drift


create new tag


Topic attachments
I Attachment Action Size Date Who Comment
1T_SdH.pngpng 1T_SdH.png manage 177 K 25 Sep 2009 - 13:44 AshwinSrinivasan 1T QHE at diferent angles
8T_SdH.pngpng 8T_SdH.png manage 113 K 25 Sep 2009 - 13:56 AshwinSrinivasan 8T QHE 1
8T_around_138.PNGPNG 8T_around_138.PNG manage 29 K 25 Sep 2009 - 13:59 AshwinSrinivasan 8T hall cal around parallel
Rotator_graph.jpgjpg Rotator_graph.jpg manage 187 K 18 Sep 2009 - 11:34 AlexHamilton SdH & Hall at different theta 18/9/09
Thetameas_v_Thetaset.pngpng Thetameas_v_Thetaset.png manage 29 K 21 Sep 2009 - 13:14 AshwinSrinivasan Theta measured from Hall effect (sin-1 Rmax/R) vs Theta set
angle_cal.jpgjpg angle_cal.jpg manage 112 K 18 Sep 2009 - 04:16 AshwinSrinivasan Rotator angle callibration using hall effect
drift_with_B.PNGPNG drift_with_B.PNG manage 57 K 25 Sep 2009 - 13:53 AshwinSrinivasan drift with B
drift_with_time.PNGPNG drift_with_time.PNG manage 47 K 25 Sep 2009 - 13:52 AshwinSrinivasan rotator drift with time
hall_angle_cal_2.PNGPNG hall_angle_cal_2.PNG manage 54 K 25 Sep 2009 - 13:59 AshwinSrinivasan hall effect angle cal 2
hall_effect_angle_cal_offset.pngpng hall_effect_angle_cal_offset.png manage 138 K 20 Sep 2009 - 01:49 AshwinSrinivasan Hall effect angle callibration offset so 0 deg = parallel
hall_res_v_B_8T.PNGPNG hall_res_v_B_8T.PNG manage 38 K 25 Sep 2009 - 13:58 AshwinSrinivasan Hall resistance v B at different angles
layout2.PNGPNG layout2.PNG manage 58 K 25 Sep 2009 - 13:57 AshwinSrinivasan 8T QHE 2
layout2.pngpng layout2.png manage 74 K 25 Sep 2009 - 13:33 AshwinSrinivasan SdH data 1T_2
Topic revision: r16 - 09 Sep 2014, RoyLi
This site is powered by FoswikiCopyright © by the contributing authors. All material on this collaboration platform is the property of the contributing authors.
Ideas, requests, problems regarding Foswiki? Send feedback