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Proceedings Paper

Ultrafast magneto-optical spectroscopy of GaMnAs
Author(s): Jean Benoit Heroux; Eiji Kojima; Y. Ino; Y. Hashimoto; Shingo Katsumoto; Yasushiro Iye; Makoto Kuwata-Gonokami
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Paper Abstract

Spin dynamics in the III-V dilute magnetic semiconductor GaMnAs is investigated by photo-induced demagnetization. Experimental results obtained from two different time-dependent characterization techniques - "two color-probe" magneto-optical Kerr effect (TR-MOKE) and mid-infrared differential transmittance -- are compared. Upon photo-excitation with a 100 fs, 3.1 eV light pulse, a long demagnetization time in the hundreds of picoseconds timescale is found by TR-MOKE, indicating a spin-dependent band structure in this material. In mid-infrared measurements, a positive increase of the differential transmittance is observed in the same time interval when the sample is cooled below its Currie temperature. It is shown that this mid-infrared absorption feature is directly related to ferromagnetism in this material. The magnetism-related component of the broad DC mid-infrared absorption peak characteristic of this p-type material could be observed with this time-resolved measurement. Experimental results were simulated with a model describing the interaction between three thermal reservoirs (hole, spin and lattice) and taking thermal diffusion into account.

Paper Details

Date Published: 13 April 2005
PDF: 12 pages
Proc. SPIE 5725, Ultrafast Phenomena in Semiconductors and Nanostructure Materials IX, (13 April 2005); doi: 10.1117/12.601978
Show Author Affiliations
Jean Benoit Heroux, Univ. of Tokyo (Japan)
SQRT (Japan)
Eiji Kojima, Univ. of Tokyo (Japan)
Y. Ino, Univ. of Tokyo (Japan)
SQRT (Japan)
Y. Hashimoto, Univ. of Tokyo (Japan)
Shingo Katsumoto, Univ. of Tokyo (Japan)
Yasushiro Iye, Univ. of Tokyo (Japan)
Makoto Kuwata-Gonokami, Univ. of Tokyo (Japan)
SQRT (Japan)

Published in SPIE Proceedings Vol. 5725:
Ultrafast Phenomena in Semiconductors and Nanostructure Materials IX
Kong-Thon Tsen; Jin-Joo Song; Hongxing Jiang, Editor(s)

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