Regensburg 2002 – wissenschaftliches Programm
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DY: Dynamik und Statistische Physik
DY 22: Quantenph
änomene
DY 22.2: Vortrag
Dienstag, 12. März 2002, 11:45–12:00, H2
Metal-Insulator transitions in an integrable system – Electrons in modulated magnetic fields — •Björn Naundorf1,2 and Roland Ketzmerick1 — 1Max-Planck-Institut für Strömungsforschung and Universität Göttingen, Bunsenstr. 10, 37073 Göttingen — 2Humboldt-Universität zu Berlin, Institut für Physik, Invalidenstr. 110, 10115 Berlin
We study the wave packet dynamics and the energy spectrum of electrons in a 2D spatially modulated magnetic field with different modulation strength in the x- and y-directions. The classical dynamics of this system is known to be chaotic and avoided crossings lead to metal-insulator transitions [1,2]. This changes the spreading direction of wave packets.
In the limit of a weak magnetic modulation we derive an effective Hamiltonian, where the corresponding classical counterpart describes an integrable system. Surprisingly, we still find metal-insulator transitions accompanied by a change in the spreading direction of wave packets. This new effect for integrable systems will be explained and should be observable in experiments on semiconductor nanostructures.
0pt [1] Ketzmerick, Kruse, Geisel, PRL 80,
137 (1998)
[2] Ketzmerick, Kruse, Springsguth, Geisel, PRL 84, 2929 (2000)