Abstract
Controlling the flow of electrons by manipulating their spin is a key to the development of spin-based electronics. Recent demonstrations of electrical-gate control in spin-transistor configurations have shown great promise, but operation at room temperature remains elusive. Further progress requires a deeper understanding of the propagation of spin polarization, particularly in the high-mobility semiconductors used for devices. Here we report the application of Doppler velocimetry to resolve the motion of spin-polarized electrons in GaAs quantum wells driven by a drifting Fermi sea. We find that the spin mobility tracks the high electron mobility precisely as a function of temperature. However, we also observe that the coherent precession of spins driven by spin–orbit interaction, which is essential for the operation of a broad class of spin logic devices, breaks down at temperatures above 150 K, for reasons that are not yet understood theoretically.
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Acknowledgements
All the optical and some of the electrical measurements were carried out at Lawrence Berkeley National Laboratory and were supported by the Director, Office of Science, Office of Basic Energy Sciences, Materials Sciences and Engineering Division, of the US Department of Energy under Contract No. DE-AC02-05CH11231. Sample growth and processing and some of the transport measurements were performed at the Center for Integrated Nanotechnologies, a US Department of Energy, Office of Basic Energy Sciences user facility at Sandia National Laboratories (Contract No. DE-AC04-94AL85000).
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L.Y., J.D.K., J.O. and M.P.L. devised the experiment and wrote the manuscript. L.Y. and J.D.K. performed optical measurements and M.P.L. and L.Y. carried out transport measurements. L.Y. and J.O. performed analysis and theoretical modelling of the data. J.L.R. and D.R.T. carried out growth and fabrication of the quantum-well device.
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Yang, L., Koralek, J., Orenstein, J. et al. Doppler velocimetry of spin propagation in a two-dimensional electron gas. Nature Phys 8, 153–157 (2012). https://doi.org/10.1038/nphys2157
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DOI: https://doi.org/10.1038/nphys2157
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