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“
