Regensburg 2013 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 45: Transport in high magnetic fields / Quantum Hall effect
HL 45.2: Talk
Tuesday, March 12, 2013, 15:15–15:30, H13
Negative Magnetoresistance induced by the interplay of disorder in a High Mobility 2DEG — •Lina Bockhorn1, Igor V. Gornyi2, Alexander D. Mirlin2, and Rolf J. Haug1 — 1Institut für Festkörperphysik, Leibniz Universität Hannover, 30167 Hannover — 2Institut für Nanotechnologie, Forschungszentrum Karlsruhe, 76021 Karlsruhe
We study magneto transport in a high mobility two-dimensional electron gas (2DEG). Hall geometries are created by photolithography on a GaAs/AlGaAs quantum well containing a 2DEG. The 2DEG has an electron density of ne=3.1*1011cm−2 and a mobility of µe=11.9*106cm2/Vs. We observe a strong negative magnetoresistance around zero magnetic field, which consists of a peak around zero magnetic field and of a huge magnetoresistance at larger fields. The peak around zero magnetic is a two-dimensional effect, as concluded from tilted magnetic field measurements. The huge magnetoresistance vanishes by increasing the temperature to 800 mK, while the peak is left unchanged [1]. At low temperature (T<600 mK) the peak is induced by the interplay of smooth disorder and rare strong scatteres [2]. For higher temperature the temperature dependence of the peak is more complex, which is the result of a crossover between different regimes. At low temperature the density of the strong scatterers nS is determined by the peak. The quality of a high mobility sample can be characterized on the basis of such magnetotransport measurements.
[1] L. Bockhorn, et al., Phys. Rev. B 83, 113301 (2011)
[2] A. D. Mirlin, et al., Phys. Rev. Lett. 87, 126805 (2001)