Seminars Archive
W. Wegscheider
Abstract
Monday, October 2, 2000, 11:00
Seminar Room, ground floor, Building "T"
Sincrotrone Trieste, Basovizza
Transport Investigations on Cleaved Edge Overgrowth Quantum Wires and Superlattices
W. Wegscheider
(University of Regensburg)
ABSTRACT
Recent transport experiments along modulation-doped quantum wires are
presented. The observed power-law dependence of the plateau values of the
quantized conductance on temperature is consistent with Luttinger liquid
(LL) theory. LL behavior is also found in the non-linear current voltage
characteristics and in the temperature dependence of conductance fluctuations
superimposed on the plateaus. In addition, the effect of an atomically
precise periodic potential on high mobility electrons induced by a gate
was studied. Pronounced negative differential resistance at small applied
electric fields is attributed to electron localization due to Bloch oscillations.
In magnetotransport experiments the minigap of the artificial band-structure
shows up in the form of open electron orbits and magnetic
breakdown. In structures with more than one occupied subband striking
quantum interference oscillations are observed. Within a semiclassical
framework, they are recognized either as self-interference along closed
orbits, many of them rendered possible by magnetic breakdown between Fermi
contour segments of the artificial bandstructure, or as a "Aharonov-Bohm"
type interference enhanced backscattering. The well-known commensurability
(Weiss) oscillations appear as a special case of the latter mechanism.
