Münster 1997 – wissenschaftliches Programm

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TT: Tiefe Temperaturen

TT 10: Niederdimensionale Systeme, Lokalisierung

TT 10.11: Vortrag

Dienstag, 18. März 1997, 17:00–17:15, F1

Phase Diagram of Localization in a Magnetic Field      — •T. Dröse¹, M. Batsch², I. Zharekeshev¹, and B. Kramer¹ — ¹I. Institut für Theoretische Physik, Universität Hamburg, Jungiusstraße 9, D-20355 Hamburg — ²Physikalisch-Technische Bundesanstalt, Bundesallee 100, D-38116 Braunschweig

The phase diagram of localization is calculated numerically for a three dimensional disordered system in presence of a magnetic field modelled by an Anderson-Hamiltonian with Peierls phase factors in the hopping matrix elements. The magnetic field causes a continuous shift of the mobility edge trajectory in the energy-disorder parameter space. In the band center, the critical points oscillate as a function of the number of flux quanta through a unit cell with a periodicty of half a flux quantum. Near the phase boundary, localized states become delocalized when a magnetic field is applied. At the band edge we observe a periodicity of one flux quantum per unit cell and for small disorders delocalized states near the transition localize. This behavior can be directly related to different localization mechanisms.