Local density of states in disordered two-dimensional electron gases at high magnetic field

Thierry Champel, Serge Florens

Published 2009-04-21, updated 2009-10-02Version 2

Motivated by high-accuracy scanning tunneling spectroscopy measurements on disordered two-dimensional electron gases in strong magnetic field, we present an exact solution for the local density of states (LDoS) of electrons moving in an arbitrary potential smooth on the scale of the magnetic length, that can be locally described up to its second derivatives. We use a technique based on coherent state Green's functions, allowing us to treat on an equal footing confining and open quantum systems. The energy-dependence of the LDoS is found to be universal in terms of local geometric properties, such as drift velocity and potential curvature. We also show that thermal effects are quite important close to saddle points, leading to an overbroadening of the tunneling trajectories.