Dresden 2006 – scientific programme

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HL: Halbleiterphysik

HL 9: Poster I

HL 9.8: Poster

Monday, March 27, 2006, 15:15–17:45, P3

Magnetotransport of Ga_1−xMn_xAs on (001) and (311)A GaAs — •Ursula Wurstbauer, Matthias Reinwald, Matthias Döppe, Dieter Schuh, Dieter Weiß, and Werner Wegscheider — Universität Regensburg, 93040 Regensburg, Germany

We have studied Ga_1−xMn_xAs grown by low-temperature molecular beam epitaxy (LT-MBE) on GaAs (001) and (311)A substrates. In-plane and out-of-plane magnetotransport measurements clearly reveal an anomalous Hall effect (AHE) and a giant planar Hall effect (GPHE). Rotating the samples in the field, the magnetic anisotropy relative to the crystal orientation can be deduced. The (001) samples show for in-plane measurements a cubic anisotropy with the hard axis aligned along the [1-10] and [110] directions and an easy axis along [100] and [0-10]. Additional an uniaxial anisotropy with the hard axis along the [001] direction and the easy axis parallel to the surface was observed by out-of-plane measurements.
Unlike these, the (311)A samples exhibit for both in-plane and out-of-plane measurements a complex superposition of the AHE and the GPHE.
In addition, we compared post growth annealing with an in-situ annealing method using an As capping layer. In both cases we found an increase of T_c.