Phys. Rev. B 87, 245406 (2013) [9 pages]

Origins of conductance anomalies in a p-type GaAs quantum point contact

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Y. Komijani*, M. Csontos, T. Ihn, and K. Ensslin
Solid State Physics Laboratory, ETH Zurich, 8093 Zurich, Switzerland

Y. Meir
Physics Department, Ben Gurion University, Beer Sheva 84105, Israel

D. Reuter and A. D. Wieck
Angewandte Festkörperphysik, Ruhr-Universität Bochum, 44780 Bochum, Germany

Received 23 January 2013; published 4 June 2013

Low-temperature transport measurements on a p-GaAs quantum point contact are presented which reveal the presence of a conductance anomaly that is markedly different from the conventional “0.7 anomaly.” A lateral shift by asymmetric gating of the conducting channel is utilized to identify and separate different conductance anomalies of local and generic origins experimentally. While the more generic 0.7 anomaly is not directly affected by changing the gate configuration, a model is proposed which attributes the additional conductance features to a gate-dependent coupling of the propagating states to localized states emerging due to a nearby potential imperfection. Finite bias conductivity measurements reveal the interplay between the two anomalies consistently with a two-impurity Kondo model.

©2013 American Physical Society

73.23.-b, 73.63.-b

*Now at Department of Physics and Astronomy, University of British Columbia, Vancouver, BC, Canada V6T 1Z1;

Now at Department of Physics, Budapest University of Technology and Economics, 1111 Budapest, Hungary.

Now at University Paderborn, Department Physik, Warburger Straße 100, 33098 Paderborn, Germany.