Berlin 2008 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 26: III-V semiconductors I
HL 26.1: Vortrag
Dienstag, 26. Februar 2008, 15:45–16:00, EW 202
Current-regulated giant anisotropic magnetoresistance in ultra thin (Ga,Mn)As — •Rashid Gareev1, Markus Schlapps1, Janusz Sadowski2, Werner Wegscheider1, and Dieter Weiss1 — 1Institute of Experimental and Applied Physics, University of Regensburg, Universitätstrasse 31, 93040 Regensburg, Germany — 2MAX-Lab, Lund University, 22100 Lund, Sweden
We describe the way to regulate giant anisotropic magnetoresistance (GAMR) in ultra thin (Ga,Mn)As by changing the amplitude of alternating current across a Hall bar. The GAMR effect is observed in the planar geometry of current below the metal-insulator transition (MIT) at T<10K in 5 nm-thick Ga0.95Mn0.05As films after annealing in optimized conditions. The GAMR manifests itself in magnetization-dependent high- and low-resistance states along different crystallographic directions. From the angular dependences of GAMR in magnetic fields of different orientation we show that in high resistive state holes are strongly localized. We demonstrate that in the localized regime a decrease of the current amplitude is accompanied by an enhancement of the GAMR. The longitudinal resistance(corresponds to the sheet resistance) change between non-equivalent easy axes exceeds ~100% at a current amplitude I=0.2nA. The dependence of the GAMR on the current strength we ascribe to suppression of e-e interactions and hole delocalization by electric field.