Dresden 2009 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 9: Poster 1

HL 9.78: Poster

Montag, 23. März 2009, 14:30–17:00, P2

Transport properties of magnetic-codoped two-dimensional hole system — •Stefan Knott, Ursula Wurstbauer, and Wolfgang Hansen — Institut für Angewandte Physik, Universität Hamburg, 20355 Hamburg

The interaction of localized magnetic moments with a two dimensional hole system (2DHS) is studied with low-temperature magneto-transport measurements on molecular beam epitaxially grown InAs or InAlGaAs quantum-well structures that are C-modulation and Mn co-doped. Measurements in magnetic fields applied perpendicular to the 2DHS reveal the typical transport behaviour of a two-dimensional charge carrier system indicated by Shubnikov-de Haas oscillations and quantum-Hall plateaus. Investigations at milli-Kelvin temperatures show a metal-insulator transition in the low field region. The fully spin-polarized quantum Hall state at filling factor ν = 1 is very pronounced, i.e. over a field range of more than 4 T the longitudinal resistance vanishes and the Hall resistance is constant. Surprisingly, the ν = 2 state seems to be fully suppressed whereas the ν = 3 state is clearly resolved by an indistinct structure in the Hall resistance and a minimum in the longitudinal resistance. Transport measurements in tilted magnetic fields are carried out to resolve the nature of the observed quantum-Hall states.