Experiments to 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.

DFG Meeting University of Regensburg MOTIVATION 06/07/08 Experiments to probe the inverse Spin-Hall Effect in GaAs Spin-Hall-Structure x y z I I V≠0 L SH FM

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 Al 2 O 3 tunneling barrier in Al Hall-Bar. Spin detection without magnetic materials. Spincurrent induces due to spin-orbit scattering a transversve Spin-Hall imbalance → U SH External B-field defines direction of spins AFM image, S.O. Valenzuela et al., Nature Lett. 442, 13 (2006)

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 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, (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.Awschalom University of Regensburg DFG Meeting „Halbleiter-Spintronik“

DFG Meeting University of Regensburg SPIN-HALL STRUCTURE 06/07/08 Experiments to probe the inverse Spin-Hall Effect in GaAs S.O. Valenzuela, M. Trinkham, Electrical detection of spin currents: The spincurrent induced Hall effect, Appl. Phys. 101 (2007)