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HL: Fachverband Halbleiterphysik

HL 31: Poster II

HL 31.19: Poster

Dienstag, 26. Februar 2008, 16:30–19:00, Poster D

Spin-splitting in the magnetotransport of tunnel-coupled AlGaAs/GaAs quantum point contacts — •S. S. Buchholz¹, P. S. Zapp¹, S. F. Fischer¹, U. Kunze¹, D. Schuh², and G. Abstreiter³ — ¹Werkstoffe und Nanoelektronik, Ruhr-Universität Bochum — ²Experimentelle und Angewandte Physik, Universität Regensburg — ³Walter-Schottky Institut, Technische Universität München

Spin-split subbands of one-dimensional electron systems are particularly interesting in order to investigate spin-related phenomena in coherent electron transport. In this work we study quantum point contacts (QPCs) prepared from double quantum well AlGaAs/GaAs-heterostructures by atomic force microscopy and wet chemical etching [1]. In such systems mode coupling can occur and be manipulated in longitudinal magnetic fields [2,3]. Here, we focus on transport properties and mode spectroscopy in perpendicular magnetic fields. A top gate voltage (V_tg) controls the occupation of 1D subbands in both stacked QPCs, a back gate voltage (V_bg) influences the occupation of mainly the bottom QPC, and cooling under back gate voltage allows the tuning of the bottom QPC confining potential. We record the conductance and transconductance with respect to V_tg, V_bg and magnetic fields. We observe a rich variety of level splittings and seek understanding of mode coupling between spin-subbands. [1] S.F. Fischer et al., Nature Physics 2, 91 (2006). [2] S.F. Fischer et al., Phys. Rev. B 74, 115324 (2006). [3] L.G. Mourokh et al., Appl. Phys. Lett. 90, 132108 (2007).