experiments to probe the inverse spin-hall effect in gaas

Experimentsto probe

the inverse Spin-Hall Effect in GaAs

U. Pfeuffer, R. Neumann, D. Schuh, W. Wegscheider, D. Weiss

7. June 2008 University of Regensburg

DFG Meeting„Halbleiter-Spintronik“

DFG Meeting University of Regensburg

CONTENT

06/07/08 Experiments to probe the inverse Spin-Hall Effect in GaAs

Motivation

Spin-Hall Structure

Sample Preparation

Measurements

Conclusion

DFG Meeting University of Regensburg

MOTIVATION

06/07/08 Experiments to probe the inverse Spin-Hall Effect in GaAs

Spin-Hall Effect

Electric field induces transverse spin-current due to spin-orbit scattering.

Inverser Spin-Hall Effect

Spincurrent induces a transverse charge-current.

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DFG Meeting University of Regensburg

MOTIVATION

06/07/08 Experiments to probe the inverse Spin-Hall Effect in GaAs

Spin-Hall-Structure

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DFG Meeting University of Regensburg

MOTIVATION

06/07/08 Experiments to probe the inverse Spin-Hall Effect in GaAs

Valenzuela & Trinkham Electrical measurements in diffusive metallic conductor.

Spincurrent injected out of ferromagnetic CoFe through Al2O3 tunneling barrier in Al Hall-Bar.

Spin detection without magnetic materials.

Spincurrent induces due to spin-orbit scatteringa transversve Spin-Hall imbalance → USH

External B-field defines direction of spins

AFM image, S.O. Valenzuela et al., Nature Lett. 442, 13 (2006)

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DFG Meeting University of Regensburg

MOTIVATION

06/07/08 Experiments to probe the inverse Spin-Hall Effect in GaAs

Valenzuela & Trinkham

DFG Meeting University of Regensburg

SAMPLE PREPARATION

06/07/08 Experiments to probe the inverse Spin-Hall Effect in GaAs

Material

3.2 Preparation

- Zn pads annealing @ 500°C- Hall-Bar (acetic acid)- Au contacts- EBL- Fe sputtering + Au (80nm + 100nm)

Wafer D070313B (grown by D. Schuh, Workgroup W. Wegscheider, University of Regensburg)

DFG Meeting University of Regensburg

MEASUREMENTS

06/07/08 Experiments to probe the inverse Spin-Hall Effect in GaAs

Sample 1 „bad sample“

DFG Meeting University of Regensburg

MEASUREMENTS

06/07/08 Experiments to probe the inverse Spin-Hall Effect in GaAs

Sample 1 „bad sample“

DFG Meeting University of Regensburg

MEASUREMENTS

06/07/08 Experiments to probe the inverse Spin-Hall Effect in GaAs

Sample 1 „bad sample“

DFG Meeting University of Regensburg

MEASUREMENTS

06/07/08 Experiments to probe the inverse Spin-Hall Effect in GaAs

Sample 1 „bad sample“

Change of polarization of injected current ?

J. Moser et al.Appl. Phys. Lett. 89, 162106 (2006)

DFG Meeting University of Regensburg

MEASUREMENTS

06/07/08 Experiments to probe the inverse Spin-Hall Effect in GaAs

Reproducibility

DFG Meeting University of Regensburg

MEASUREMENTS

06/07/08 Experiments to probe the inverse Spin-Hall Effect in GaAs

Sample 2 „good sample“

DFG Meeting University of Regensburg

MEASUREMENTS

06/07/08 Experiments to probe the inverse Spin-Hall Effect in GaAs

Sample 2 „good sample“

DFG Meeting University of Regensburg

MEASUREMENTS

06/07/08 Experiments to probe the inverse Spin-Hall Effect in GaAs

Sample 2 „good sample“

DFG Meeting University of Regensburg

CONCLUSION & OUTLOOK

06/07/08 Experiments to probe the inverse Spin-Hall Effect in GaAs

Measured signal looks like inverse „Spin-Hall-Effect“ on GaAs

Further tests

Non-ferromagnetic injector

Structure with different distances from injector

Thank You For Your Attention

"The most exciting aspect of this finding is that you don't know exactly where it's going to lead“

D.D.AwschalomUniversity of Regensburg

DFG Meeting„Halbleiter-Spintronik“