Abstract
The controlled creation, manipulation and detection of spin-polarized currents by purely electrical means remains a central challenge of spintronics. Efforts to meet this challenge by exploiting the coupling of the electron orbital motion to its spin, in particular Rashba spin–orbit coupling, have so far been unsuccessful. Recently, it has been shown theoretically that the confining potential of a small current-carrying wire with high intrinsic spin–orbit coupling leads to the accumulation of opposite spins at opposite edges of the wire, though not to a spin-polarized current. Here, we present experimental evidence that a quantum point contact—a short wire—made from a semiconductor with high intrinsic spin–orbit coupling can generate a completely spin-polarized current when its lateral confinement is made highly asymmetric. By avoiding the use of ferromagnetic contacts or external magnetic fields, such quantum point contacts may make feasible the development of a variety of semiconductor spintronic devices.
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Acknowledgements
P.D. would like to thank J.J. Krich for interesting and useful discussions. The authors are thankful to J. Marcus and R. Schrott for technical help. This work was supported by National Science Foundation (NSF) awards ECCS 0725404 and DMR 0710581.
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P.D. conceived and designed the experiments, participated in some measurements, analysed the data and wrote the manuscript. S.M.S.R. made the samples and performed most of the experiments. J.W. and M.C. carried out the NEGF numerical calculations. A.T.N. and S.E.U. conducted theoretical calculations based on free-electron Hamiltonian. S.T.H. and R.S.N. contributed materials, analysis and experimental tools. M. J. contributed materials. M.M. helped with the experiments. All authors discussed the results and commented on the manuscript.
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Debray, P., Rahman, S., Wan, J. et al. All-electric quantum point contact spin-polarizer. Nature Nanotech 4, 759–764 (2009). https://doi.org/10.1038/nnano.2009.240
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DOI: https://doi.org/10.1038/nnano.2009.240
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