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HL: Fachverband Halbleiterphysik

HL 23: Transport in high magnetic field/quantum-Hall-effect

HL 23.3: Vortrag

Dienstag, 24. März 2009, 14:30–14:45, BEY 154

Signatures of neutral quantum Hall modes in transport through low-density constrictions — •Bernd Rosenow¹ and Bertrand I. Halperin² — ¹Max-Planck Insitut für Festkörperforschung, D-70569 Stuttgart, Germany — ²Physics Department, Harvard University, Cambridge, MA 02138, USA

Constrictions in fractional quantum Hall (FQH) systems not only facilitate backscattering between counter-propagating edge modes, but also may reduce the constriction filling fraction ν_c with respect to the bulk filling fraction ν_b. If both ν_b and ν_c correspond to incompressible FQH states, at least part of the constriction region is surrounded by composite edges, whose low energy dynamics is characterized by a charge mode and one or several neutral modes. In the incoherent regime, decay of neutral modes describes the equilibration of composite FQH edges, while in the limit of coherent transport, the presence of neutral modes gives rise to universal conductance fluctuations. In addition, neutral modes renormalize the strength of scattering across the constriction, and thus can determine the relative strength of forward and backwards scattering.