Dresden 2003 – wissenschaftliches Programm

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HL: Halbleiterphysik

HL 5: Quantenpunkte und -dr
ähte: Transporteigenschaften I

HL 5.11: Vortrag

Montag, 24. März 2003, 13:00–13:15, POT/81

Electron localization in disordered quantum wires — •Alexander Struck, Stefan Kettemann, and Bernhard Kramer — I. Institut f. Theoretische Physik, Universitaet Hamburg, Jungiusstr. 9, 20355 Hamburg

Qualitative and quantitative numerical investigations of the disorder-induced localization-delocalization transition of 2D electron states in the quantum Hall regime were primarily concerned with systems fulfilling periodic boundary conditions. In this manner, conducting edge channels overlapping regions of localized bulk states could be avoided in order to scrutinize the localization properties in detail.

However, the situation is different in experimental setups where edge states can occur and contribute to the conductivity in addition to the extended bulk states. It is therefore important to investigate the localization properties of 2D electrons in the presence of disorder and a strong perpendicular magnetic field which are confined by a potential.

We present numerical calculations for disordered quantum wires, i.e. while confining one side of a rectangular sample, we retain boundary conditions along the other direction. As a model for confinement, a parabolic electrostatic potential is assumed. The special feature of this model is that only edge states exist and Landau functions as eigenfunctions for the case of vanishing disorder are still valid with a renormalized magnetic length. We find that an additional disorder potential modelled by Gaussian scatterers couples the two edge channels and leads to electron localization in the center of the wire.