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TT: Tiefe Temperaturen

TT 20: Niederdimesnionale Systeme, Magnetotransport, Quantenhalleffekt II

TT 20.1: Vortrag

Donnerstag, 29. März 2001, 09:30–09:45, A

Non-universal behavior of scattering between fractional quantum Hall edges — •B. Rosenow^1,2 and B.I. Halperin² — ¹Insitut für Theoretische Physik, Universität zu Köln, Zülpicher Straße 77, 50937 Köln, Germany — ²Physics Department, Harvard University, Cambridge, MA 02138, USA

Among the predicted properties of fractional quantum Hall states are fractionally charged quasi-particles and conducting edge-states described as chiral Luttinger liquids. In a system with a narrow constriction, tunneling of quasi-particles between states at different edges can lead to resistance and to shot noise. The ratio of the shot noise to the backscattered current, in the weak scattering regime, measures the fractional charge of the quasiparticle, which has been confirmed in several experiments. However, the nonlinearity of the resistance predicted by Luttinger liquid theory was not observed.

As a possible explanation for these discrepancies, we consider a model where a smooth edge profile leads to formation of additional edge states. Coupling between the current carrying edge mode and the additional phonon like mode can lead to nonuniversal exponents in the current-voltage characteristic, while preserving the ratio between shot-noise and the back-scattered current. For special values of the coupling, one can obtain Fermi-liquid like behavior as observed in experiments.