Time: 16:00

Location: zaal E

Werner Wegscheider from University of Regensburg will talk on "Huge metastability and reentrant phases in a magnetic two-dimensional hole system".

Magnetotransport studies on Mn modulation-doped InAs quantum well
structures reveal a magnetic field driven metal-insulator transition.
The transition to the insulating regime is accompanied by a hysteretic
behavior and abrupt resistance changes over several orders of magnitude. This effect occurs in coexistence with typical quantized transport properties in a two-dimensional charge carrier system. These remarkable experimental findings are attributed to the role of the Mn impurities, which provide a localized spin S=5/2 and act as an acceptor. In an intermediate regime of hole densities metallic-like conductivity is
observed in an applied perpendicular magnetic field. When the magnetic
field is decreased, a continuous cross-over to a strongly localized
regime is observed which is interpreted as a result of the increased
magnetic disorder.