Regensburg 2004 – wissenschaftliches Programm

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HL: Halbleiterphysik

HL 44: Poster II

HL 44.5: Poster

Donnerstag, 11. März 2004, 16:30–19:00, Poster A

Magnetotransport in (GaMn)As/MnAs and (GaInMn)As/MnAs paramagnetic-ferromagnetic hybrids — •S. Ye, P.J. Klar, W. Heimbrodt, M. Lampalzer, S. Hara, and W. Stolz — FB Physik und WZMW, Philipps-Universität, Marburg

The (GaMn)As/MnAs and (GaInMn)As/MnAs paramagnetic-ferromagnetic granular hybrids were grown by metal organic vapour phase epitaxy. By varying the growth conditions different cluster sizes and different orientations of the MnAs clusters with respect to the matrix can be obtained. We have performed magnetoresistance (MR) and Hall measurements in magnetic fields up to 10 T and hydrostatic pressures up to 15 kbar at temperatures between 1.6 and 300 K. The (GaMn)As/MnAs system exhibits a large MR (≈ 160%) at 10 T, and changes from a negative to a positive MR with increasing temperature. The MR depends strongly on the cluster size, the chosen transport geometry and an the applied pressure. However the observed effects for the (GaInMn)As/MnAs are considerably smaller even for comparable cluster sizes and similar layer thickness. It is suggested that the interaction between MnAs ferromagnetic clusters and paramagnetic matrix plays an important role for the magnetotransport in such magnetic semicondutor hybrids, which can be adjusted by the cluster size, the chosen transport geometry and the type of paramagnetic matrix material.