Regensburg 2004 – wissenschaftliches Programm

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HL: Halbleiterphysik

HL 35: Symposium Ferromagnetische Halbleiter

HL 35.4: Vortrag

Donnerstag, 11. März 2004, 11:45–12:15, H15

Disorder effects in diluted magnetic semiconductors — •Carsten Timm — Institut für Theoretische Physik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin

Diluted magnetic semiconductors (DMS) are promising materials for technological applications as well as interesting from the basic-physics point of view. In the last years it became clear that disorder plays a crucial role in DMS due to the presence of many charged defects and the random positions of impurity spins. In this talk the effect of disorder on transport properties and magnetism in DMS is discussed. It is argued that the impurity positions are partially correlated. These correlations are crucial for the understanding of magnetic properties and the observed metal-insulator transition. In the final part of the talk, a calculation of the RKKY-like interaction between impurity spins is presented, starting from a realistic band structure. This interaction is found to be highly anisotropic, which, together with the disorder, leads to magnetic frustration and might explain the incomplete magnetization at low temperatures.