Dresden 2009 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 24: Invited Talk Neumaier
HL 24.1: Hauptvortrag
Dienstag, 24. März 2009, 14:45–15:30, HSZ 01
Phase coherent transport in (Ga,Mn)As — •D. Neumaier1, K. Wagner1, U. Wurstbauer1,2, M. Reinwald1, W. Wegscheider1, and D. Weiss1 — 1Universität Regensburg — 2Universität Hamburg
The low temperature conductance of mesoscopic samples is altered by quantum interference effects, caused by the electron’s wave nature. Information on the relevant quantum mechanical transport properties is needed to understand charge transport in general and to design more sophisticated structures in particular. In this talk I will review our investigations on universal conductance fluctuations [1,2], Aharonov-Bohm oscillations [2] and weak localization [2,3] in the diluted magnetic semiconductor (Ga,Mn)As. Analyzing universal conductance fluctuations in (Ga,Mn)As nanowires results in a phase coherence length of ≈100 nm at 20 mK with a 1/√T temperature dependency. This agrees well with values extracted from the amplitude of periodic Aharonov-Bohm oscillations observed in (Ga,Mn)As nanorings. To investigate weak localization in (Ga,Mn)As, arrays of wires were fabricated to suppress universal conductance fluctuations by ensemble averaging. The magnetoconductance of the (Ga,Mn)As wire arrays displays a pronounced low temperature anomaly ascribed to weak localization. A comparison of phase coherent transport in (Ga,Mn)As with nonmagnetic materials and conventional ferromagnets will be given.
[1] K. Wagner et al PRL 97, 056803 (2006).
[2] D. Neumaier et al. NJP 10 055016 (2008).
[3] D. Neumaier et al PRL 99, 116803 (2007).