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Cross-sectional imaging of spin injection into a semiconductor

Nature Physics volume 3, pages 872–877 (2007)Cite this article

Abstract

Recent discoveries of phenomena that relate electronic transport in solids to the spin angular momentum of the electrons are the fundamentals of spin electronics (spintronics). The first proposed conceptual spintronic device, the spin field-effect transistor—which has not yet been successfully implemented—requires the creation and detection of spin-polarized currents in a semiconductor. Whereas electrical spin injection from a ferromagnetic metal into GaAs has been achieved recently, the detection techniques used up to now have drawbacks like the requirement of large magnetic fields or limited information about the spin polarization in the semiconductor. Here we introduce a method that, by observation across a cleaved edge, enables us to directly visualize fully remanent electrical spin injection into bulk GaAs from a ferromagnetic contact, to image the spin-density distribution in the semiconductor in a cross-sectional view and to separate the effects of spin diffusion and electron drift.

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Figure 1: Schematic diagram of the spin-injection experiment (lateral transport) and basic magnetic behaviour.
Figure 2: Cross-sectional imaging of the injected spin polarization in the lateral-current geometry (all measurements at T=9 K).
Figure 3: Characterization of the injected spin polarization in the vertical-current geometry.

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Acknowledgements

This work has been supported by the Deutsche Forschungsgemeinschaft (DFG) under FOR 370 and SFB 689. We thank B. Muermann and J. Ehehalt for assistance with programming some of the measurement procedures, P. Chen for characterization of the GaAs materials and J. Fabian for discussions.

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Authors and Affiliations

  1. Institut für Experimentelle und Angewandte Physik, Universität Regensburg, 93040 Regensburg, Germany

    P. Kotissek, M. Bailleul, M. Sperl, A. Spitzer, D. Schuh, W. Wegscheider, C. H. Back & G. Bayreuther

  2. Institut de Physique et Chimie des Matériaux de Strasbourg, UMR 7504 ULP-CNRS, 23 rue du Loess, BP 43, 67034 Strasbourg, France

    M. Bailleul

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  1. P. Kotissek
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  2. M. Bailleul
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  3. M. Sperl
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  4. A. Spitzer
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  8. G. Bayreuther
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Contributions

P.K. designed and carried out the experiments, analysed the data and prepared the manuscript; M.B. conceived the main experiment, developed the theoretical data analysis and contributed to the manuscript; M.S. carried out the SQUID measurements and contributed to the manuscript; A.S. carried out part of the sample preparation; D.S. grew the semiconductor materials; W.W. devised the project and contributed materials; C.H.B. provided support for the optical measurements and contributed to the manuscript; G.B. devised the project, contributed to the data analysis and wrote the paper.

Corresponding author

Correspondence to G. Bayreuther.

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Supplementary Information

Supplementary Figures 1 and 2 (PDF 88 kb)

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Kotissek, P., Bailleul, M., Sperl, M. et al. Cross-sectional imaging of spin injection into a semiconductor. Nature Phys 3, 872–877 (2007). https://doi.org/10.1038/nphys734

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