Berlin 2012 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 20: Focus Session: Magnetic Semiconductors (jointly with MA)

HL 20.6: Talk

Monday, March 26, 2012, 17:45–18:00, EW 202

Anomalous Hall effect in Mn doped, p-type InAs quantum wells — •Dieter Vogel, Christina Wensauer, Ursula Wurstbauer, Dieter Schuh, Werner Wegscheider, and Dieter Weiss — Institute for Experimental and Applied Physics, University of Regensburg, 93040 Regensburg, Germany

We measured the Hall resistivity in InAs:Mn quantum wells (QWs), containing a two-dimensional hole gas, as a function of temperature, carrier density and manganese concentration. Earlier experiments on these Mn doped InAs QWs indicated the important role of p-d exchange coupling between holes and Mn magnetic moments, giving rise to hysteretic magnetoresistance and thermal bistability of the longitudinal resistance [1]. In the present work we find that this paramagnetic two-dimensional system features a considerable anomalous Hall effect (AHE) whose size increases with decreasing temperature and increasing Mn concentration. Surprisingly, the sign of the anomalous Hall coefficient is negative. A first analysis of the data shows that the skew scattering contribution is rapidly suppressed as temperature increases. Furthermore, the empirical scaling between Hall and longitudinal conductivity in the bad-metal-hopping regime [2], σ_xy∼ σ_xx^γ, with γ = 1.6, seems to be valid also in our system. Finally, we discuss the possibility to separate the intrinsic and the extrinsic scattering contribution following recent work by [3].
U. Wurstbauer et al., Nature Physics 6, 955 (2010)
N. Nagaosa et al., Rev. Mod Phys. 82, 1539 (2010)
A. Shitade and N. Nagaosa, ArXiv ID 1109.5463 (2011).