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Overview STT200900625A

Overview STT200900625A. Q2 Resistance Overview. Column 25 contains other measurements. 300 nm x 600 nm. 450 nm x 900 nm. Two rows have relatively low resistance (M and N). The complete block on the right hand side has low resistance and only 3 opens.

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Overview STT200900625A

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  1. Overview STT200900625A

  2. Q2 Resistance Overview Column 25 contains other measurements 300 nmx 600 nm 450 nmx 900 nm • Two rows have relatively low resistance (M and N). • The complete block on the right hand side has low resistance and only 3 opens. • Red lower right corner indicates that MR was tested.

  3. Q2 Resistance Scaling(all points) Detail All R • If the resistance is plotted for all measured points, no scaling is visible.

  4. Q2 Resistance Scaling(manually selected points, all points) • This plot shows the resistance scaling for the junctions that seemed to be good. • There could be scaling with area (see detail next slide).

  5. Q2 Resistance Scaling(manually selected points, detail) • There could be some scaling, at least the points are not randomly distributed. • The red square indicates the good junction. • The line indicates a possible scaling law.

  6. Q2 Typical Hysteresis Curves C23 200 nm x 300 nm • Many junctions show a magnetical signal. • It is never hysteretic, but always single spikes up or down at about 80 mT. • The next slide just shows many of these curves for different samples.

  7. Q2, Collection of Hysteresis Curves • No selection, these are the curves like measured • Most of them show some MR M23: 300 x 600 N22: 450 x 900 M22: 300 x 600 G22: 180 x 260 J22: 160 x 280 H22: 180 x 200 M21: 300 x 600 N16: 450 x 900 Continued on next page N21: 450 x 900

  8. Q2, Collection of Hysteresis Curves, cont. F22: 180 x 300 E22: 180 x 340 C22: 200 x 300 A22: 250 x 400 B22: 200 x 400 B22: 200 x 400 • The curves were not selected by hand. • Most have peaks at around +- 80 mT. • The peaks show both signs, sometimes for the same junction. • The sweeps are not always reproducible (see e.g. B22; domain walls?).

  9. Q2 Field dependence 22B: 200 x 400 In plane Perp. plane Peaks switched sign. • The measurement was repeated twice for in-plane and out-of-plane fields. • The peaks shift, but are not reproducible for one field direction either.

  10. Q2 Non-typical Hysteresis Curve D22: 200 x 350 0.89% MR • This is the only good junction. • The resistance is not different from other junctions, it is in the middle of the other junctions.

  11. Q2 Serpentine Pattern • Magnetoresistance of the serpentine pattern on Q2 with some initial drift.

  12. Q2 After Top ElectrodeResistance Overview, High-speed 4-point • Sample 26A has hysteretic behaviour.

  13. Q2 After Top Electrode High-speed 4-point 26A: 150 x 300 • 0.2% MR. • These measurements cannot be done with the picoprobes.

  14. Q2 After Top ElectrodeCurrent Sweep 26A: 150 x 300 High-speed 4-point Corrected for heating Raw data • Current Sweep does not indicate current-induced excitations or switching.

  15. Q3 Resistance Overview • Resistance is worse than on Q2. • Again, junctions with similar resistance cluster.

  16. Q3 22N Hysteresis 30 sweeps averaged • The peak appears on Q3, too. • Averaged over 30 sweeps the peak disappears, because it is not stable.

  17. Q3 MR Serpentine Pattern • Magnetoresistance of the serpentine pattern on Q3 looks worse than on Q2.

  18. Q4 Resistance Overview

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