Regensburg 2002 – wissenschaftliches Programm

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HL: Halbleiterphysik

HL 18: Symposium: Physics in High Magnetic Fields

HL 18.6: Fachvortrag

Dienstag, 12. März 2002, 17:00–17:30, H15

High magnetic fields in semiconductor nanostructures — •U. Zeitler¹, I. Hapke-Wurst¹, H. Frahm², R. J. Haug¹, K. Pierz³, and A. G. M. Jansen⁴ — ¹Institut für Festkörperphysik, Universität Hannover, Appelstraße 2, D-30167 Hannover — ²Institut für theoretische Physik, Universität Hannover — ³PTB Braunschweig, 38116 Braunschweig — ⁴Grenoble High Field Magnet Laboratory, MPIF-CNRS, Grenoble, France

The influence of high magnetic fields to semiconductor nanostructures can lead to spectacular field induced effects. In this talk we will present two prominent examples.

In the first part we will show how an in-plane magnetic field applied to the two-dimensional electron system of a Si/SiGe heterostructure induces pronounced transport anisotropies in the magnetoresistance [1]. We will propose that these anisotropies can be explained by the formation of a unidirectional stripe phase oriented perpendicular to the in-plane field.

The second part of the talk will be devoted to magnetic field induced Fermi edge singularities observed in the resonant tunnelling through self-assembled InAs quantum dots [2]. Current steps in the I-V-characteristics assigned to single electron tunnelling evolve into extremely enhanced current peaks in high magnetic fields (B>20 T). The singularity will be shown to be due to the Coulomb interaction between the tunnelling electron on the quantum dot and the partly spin-polarized Fermi sea in the Landau quantized three-dimensional emitter.

[1] U. Zeitler et al., Phys. Rev. Lett. 86, 866 (2001).

[2] I. Hapke-Wurst et al., Phys. Rev. B. 62, 12621 (2000).