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Science 29 August 1997:
Vol. 277. no. 5330, pp. 1284 - 1287
DOI: 10.1126/science.277.5330.1284
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Reports

Room-Temperature Spin Memory in Two-Dimensional Electron Gases

J. M. Kikkawa, I. P. Smorchkova, N. Samarth, D. D. Awschalom *

Time-resolved Kerr reflectivity of two-dimensional electron gases in II-VI semiconductors provides a direct measure of electron spin precession and relaxation over a temperature range from 4 to 300 kelvin. The introduction of n-type dopants increases the electronic spin lifetimes several orders of magnitude relative to insulating counterparts, a trend that is also observed in doped bulk semiconductors. Because the electronic spin polarization in these systems survives for nanoseconds, far longer than the electron-hole recombination lifetime, this technique reveals thousands of spin precession cycles of 15 gigahertz per tesla within an electron gas. Remarkably, these spin beats are only weakly temperature dependent and persist to room temperature.

J. M. Kikkawa and D. D. Awschalom, Department of Physics, University of California, Santa Barbara, CA 93106, USA.
I. P. Smorchkova and N. Samarth, Department of Physics, The Pennsylvania State University, University Park, PA 16802, USA.
*   To whom correspondence should be addressed.

Volume 277, Number 5330, Issue of 29 August 1997, pp. 1284-1287
©1997 by The American Association for the Advancement of Science.

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