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Phys. Rev. Lett. 103, 137201 (2009) [4 pages]

Electronic Structure of Ferromagnetic Semiconductor Ga1-xMnxAs Probed by Subgap Magneto-optical Spectroscopy

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G. Acbas1, M.-H. Kim1, M. Cukr2, V. Novák2, M. A. Scarpulla3, O. D. Dubon3, T. Jungwirth2,4, Jairo Sinova5,2, and J. Cerne1
1Department of Physics, University at Buffalo, SUNY, Buffalo, New York 14260, USA
2Institute of Physics ASCR, v.v.i., Cukrovarnick 10, 162 53 Praha 6, Czech Republic
3Department of Materials Science and Engineering and Lawrence Berkeley National Laboratory, University of California, Berkeley, California 94720, USA
4School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD, United Kingdom
5Department of Physics, Texas A&M University, College Station, Texas 77843-4242, USA

Received 1 July 2009; published 24 September 2009

We employ Faraday and Kerr effect spectroscopy in the infrared range to investigate the electronic structure of Ga1-xMnxAs near the Fermi energy. The band structure of this archetypical dilute-moment ferromagnetic semiconductor has been a matter of controversy, fueled partly by previous measurements of the unpolarized infrared absorption and their phenomenological impurity-band interpretation. Unlike the unpolarized absorption, the infrared magneto-optical effects we study are intimately related to ferromagnetism, and their interpretation is much more microscopically constrained in terms of the orbital character of the relevant band states. We show that the conventional theory of the disordered valence band with an antiferromatnetic exchange term accounts semiquantitatively for the overall characteristics of the measured infrared magneto-optical spectra.

© 2009 The American Physical Society

URL:
http://link.aps.org/doi/10.1103/PhysRevLett.103.137201
DOI:
10.1103/PhysRevLett.103.137201
PACS:
75.50.Pp, 71.55.Eq, 78.20.Ls, 78.66.Fd