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Phys. Rev. Lett. 95, 107001 (2005) [4 pages]

Andreev Reflection at High Magnetic Fields: Evidence for Electron and Hole Transport in Edge States

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J. Eroms* and D. Weiss
Universität Regensburg, Institut für Experimentelle und Angewandte Physik, D-93040 Regensburg, Germany

J. De Boeck and G. Borghs
IMEC, Kapeldreef 75, B-3001 Leuven, Belgium

U. Zülicke
Institute of Fundamental Sciences and MacDiarmid Institute for Advanced Materials and Nanotechnology, Massey University, Private Bag 11 222, Palmerston North, New Zealand

Received 7 April 2004; published 31 August 2005

We have studied magnetotransport in arrays of niobium filled grooves in an InAs/AlxGa1-xSb heterostructure. The critical field of up to 2.6 T permits one to enter the quantum Hall regime. In the superconducting state, we observe strong magnetoresistance oscillations, whose amplitude exceeds the Shubnikov–de Haas oscillations by a factor of about 2, when normalized to the background. Additionally, we find that above a geometry-dependent magnetic field value the sample in the superconducting state has a higher longitudinal resistance than in the normal state. Both observations can be explained with edge channels populated with electrons and Andreev-reflected holes.

© 2005 The American Physical Society

URL:
http://link.aps.org/doi/10.1103/PhysRevLett.95.107001
DOI:
10.1103/PhysRevLett.95.107001
PACS:
74.45.+c, 73.43.Qt

*Present address: Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, The Netherlands.

Electronic address: eroms@qt.tn.tudelft.nl

 
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