Regensburg 2004 – scientific programme

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HL: Halbleiterphysik

HL 14: Symposium Quanten-Hall-Systeme

HL 14.4: Talk

Tuesday, March 9, 2004, 11:45–12:15, H15

Coulomb Drag as a Probe of the Nature of Compressible States in a Magnetic Field — •Sjoerd Lok¹, K. Muraki¹, S. Kraus¹, W. Dietsche¹, K. Von Klitzing¹, D. Schuh², M. Bichler², and W. Wegscheider² — ¹Max Planck Insitut für Festkörperforschung, Heisenbergstrasse 1 70569 Stuttgart — ²Walter Schottky Insitut, Technische Universität München, Am Coulomb Wall, 85748 Garching

Magneto-drag reveals the nature of compressible states and the underlying interplay of disorder and interactions. At filling factor 3/2 a clear T^4/3 dependence is observed, which signifies the metallic nature of the N=0 Landau level. In contrast, drag in higher Landau levels reveals an additional contribution, which anomalously grows with decreasing T before turning to zero following a thermal activation law. The anomalous drag is discussed in terms of electron-hole asymmetry arising from disorder and localization, and the crossover to normal drag at high fields as due to screening of disorder.