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HL: Halbleiterphysik

HL 12: Poster I

HL 12.40: Poster

Montag, 8. März 2004, 16:30–19:00, Poster A

Density of States Tails in Random Magnetic Fields — •Riccardo Mazzarello, Stefan Kettemann, and Bernhard Kramer — I Institut fuer Theoretische Physik, Universitaet Hamburg, 20355 Hamburg, Germany

Recently, the problem of a quantum particle moving in a random magnetic field (RMF) has been met in a number of contexts in the physics of 2D-systems. For instance, in the Composite Fermion (CF) theory of the Fractional Quantum Hall Effect, electrons are transformed into particles with statistical flux attached to them: CFs experience a fictitious, statistical magnetic field proportional to their density in addition to the external one. The presence of a random, scalar potential induces fluctuations in the CFs density which give rise to a static RMF. We studied the tails of the density of states (DOS) of fermions subject to a constant magnetic field B plus a weak RMF with zero mean in the framework of the Optimum Fluctuation Method. We show that, near the centres of the broadened Landau levels, the DOS is a Gaussian, whereas the energy dependence of the DOS is non-analytic near the band edge (E=0). The B-dependence of the DOS in both regions is also estimated.