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HL: Halbleiterphysik

HL 29: Ultrakurzzeitdynamik I

HL 29.10: Vortrag

Donnerstag, 25. März 1999, 12:45–13:00, H2

Cycloidal Bloch Oscillations and Coherent Hall Effect in Biased Semiconductor Superlattices in Parallel Magnetic Field — •Yu.A. Kosevich — Max Planck Institute for Physics of Complex Systems, Noethnitzer Strasse 38, D-01187 Dresden

The influence of magnetic field, applied parallel to the layers, on Bloch oscillations and coherent electron transport in biased semiconductor superlattices is investigated. The transient coherent dynamics of the electron wave packet in time domain shorter than relaxation (dephasing) time is considered. The cycloidal coherent motion of the electron wave packet in crossed electric and magnetic fields is described analytically. The frequency of cycloidal Bloch oscillations and amplitude of the normal to the layers ac component of the electron group velocity monotonously decrease with magnetic field. The parallel component of the electron velocity has nonmonotonous magnetic field dependence, starting from zero in zero magnetic field. It is shown that narrow-miniband vertical transport in a biased superlattice in parallel magnetic field causes transient coherent dc Hall drift velocity which linearly increases with magnetic field. Nonlinear dielectric response and dynamic electron localization in biased superlattices in parallel magnetic field is described analytically. The interaction and mutual suppression of the Bloch oscillations and coherent plasmons (or magnetoplasmons) in a biased superlattice is considered. The possible anticrossing and coupling of the electronic Bloch oscillations with longitudinal optical phonons in a superlattice is described. The possibility is also emphasized of the optical excitation in a biased semiconductor superlattice of the coherent transient quasiparticles with a large (and even negative) effective mass, which can be directly measured in cyclotron-resonance-type experiments in a strong parallel magnetic field.