Dresden 2014 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 12: Topological insulators: mostly interaction with magnetic fields (with HL/O/TT)

MA 12.5: Vortrag

Montag, 31. März 2014, 16:45–17:00, POT 081

Weak antilocalization effects in systems with Dirac-like energy dispersion — •Andreas Budewitz, Mathias Mühlbauer, Bastian Büttner, Grigory Tkachov, Ewelina M. Hankiewicz, Christoph Brüne, Hartmut Buhmann, and Laurens W. Molenkamp — Universität Würzburg, Lehrstuhl für experimentelle Physik III

HgTe quantum wells (QW) have been identified as topological insulator (TI) by appearence of the QSHE [1]. It has been shown that the band structure of HgTe QWs has to be described by a four band model revealing a Dirac like dispersion [2, 3]. Here now we investigate the weak antilocalization (WAL) effect in various n-conducting HgTe QWs. We analyse the magnetoresistance of a set of quasi one-dimensional wires and clearly observe different WAL amplitudes for normal and inverted band ordering which does not depended on the structural inversion asymmetry (SIA). The data demonstrate that a non-universal Berry phase which exceeds π, the characteristic value for gapless Dirac fermions, is needed to explain the different observations in our measurements.

[1] M. König, S. Wiedmann, C. Brüne, A. Roth, H. Buhmann, L. W. Molenkamp, X.-L. Qi and S.-C. Zhang, Science 318, 766 (2007)

[2] B. A. Bernevig, T. L. Hughes and S. C. Zhang, Science 318, 1757 (2006)

[3] B. Büttner, C.-X. Liu, G. Tkachov, E. G. Novik, C. Brüne, H. Buhmann, E. M. Hankiewicz, P. Recher, B. Trauzettel, S.-C. Zhang, and L. W. Molenkamp, Nature Phys. 7, 418 (2011)