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Spin-polarized electron transport processes at the ferromagnet/semiconductor interface

Hirohata, A., Bland, J.A.C., Xu, Y.B., Guertler, C.M. and Holmes, S.N. (2000) Spin-polarized electron transport processes at the ferromagnet/semiconductor interface. IEEE Transactions on Magnetics. pp. 2827-2832. ISSN 1941-0069

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Abstract

Circularly polarized light was used to excite electrons with a spin polarization perpendicular to the film plane in ferromagnet/semiconductor hybrid structures. The Schottky characteristics at the interface were varied by using NiFe, Co and Fe as the ferromagnet. The Schottky characteristics were clearly observed with NiFe and Co/GaAs, while almost ohmic I-V characteristics were seen with Fe/GaAs. At negative bias a helicity-dependent photocurrent, dependent upon the magnetization configuration of the film and the Schottky barrier height, was detected upon modulating the polarization from right to left circular, For the magnetization along or perpendicular to the surface normal, the helicity-dependent photocurrent In or I 0, respectively, was measured. The asymmetry P=(In-I0)/(In+I0) of the helicity-dependent photocurrent decreases upon increasing the doping density of the GaAs substrates. P also decreases with photon energy h¿ as found for the polarization of photoexcited electrons in GaAs. In NiFe/GaAs samples for h¿=1.59 eV, P=16% for n+=1023 m-3 and P=-23% for p-=1025 m-3 doped substrates, i.e. P is comparable in magnitude to the theoretically predicted spin polarization of 50% for the optically pumped conduction band in GaAs. The results provide unambiguous evidence of spin-polarized electron transport through the ferromagnet/semiconductor interface and show that the Schottky barrier height controls the spin-polarized electron current passing from the semiconductor to the ferromagnet. The asymmetry data indicates that spin-polarized electrons are transmitted from the semiconductor to the ferromagnet with a high efficiency.

Item Type: Article
Copyright, Publisher and Additional Information: © 2000 IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE.
Keywords: ferromagnet/semiconductor interface, photon helicity, Schottky barrier, spin-polarized electron
Institution: The University of York
Academic Units: The University of York > Electronics (York)
Depositing User: Repository Officer
Date Deposited: 18 Dec 2006
Last Modified: 16 Oct 2014 22:50
Published Version: http://dx.doi.org/10.1109/20.908601
Status: Published
Refereed: Yes
Related URLs:
URI: http://eprints.whiterose.ac.uk/id/eprint/1858

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