Regensburg 2004 – scientific programme
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HL: Halbleiterphysik
HL 35: Symposium Ferromagnetische Halbleiter
HL 35.1: Talk
Thursday, March 11, 2004, 10:15–10:45, H15
Magnetic Anisotropy in Ferromagnetic III-Mn-V Semiconductors: Issues and Observations — •Jacek K. Furdyna — University of Notre Dame, Notre Dame, Indiana, USA
Magnetic anisotropy in III-V-based ferromagnetic (FM) semiconductor alloys (e.g., Ga1−xMnxAs) is interesting from two points of view. First, it can be “engineered” by imposing appropriate strain conditions on the FM film; and second, magnetic anisotropy is expected to play an essential role in designing spin-injection devices based on these materials. In this paper we present the information on MA in FM semiconductors obtained through a series of complementary methods: ferromagnetic resonance (FMR), planar Hall effect, direct imaging of FM domains by magneto-optical methods, and SQUID magnetization data. Special attention will be given to the recently-observed re-orientation of the easy axis in several of the III1−xMnxV alloys as a function of temperature and/or illumination, and to the somewhat surprising uniaxial anisotropy in the sample plane which some of these materials exhibit, presumably as a consequence of surface reconstruction during the growth.