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HL: Halbleiterphysik

HL 3: Spintronik I

HL 3.10: Talk

Friday, March 4, 2005, 13:00–13:15, TU P164

Magneto-transport in MnAs/GaAs:Mn paramagnetic-ferromagnetic hybrids grown by MOVPE and obtained by annealing of MBE-grown (Ga,Mn)As — •Shuangli Ye, Peter J. Klar, Wolfram Heimbrodt, Michael Lampalzer, Kerstin Volz, and Wolfgang Stolz — Department of Physics and Material Sciences Center, Philipps-University of Marburg, Germany

The MnAs/GaAs:Mn granular material consists of MnAs nanoclusters embedded in a GaAs:Mn matrix. The clusters are ferromagnetic or superparamagnetic (depending on size) at room temperature and compatibile with III-V heterostructures which makes them suitable for possible applications in magneto-optic or spintronic semiconductor devices. Here, we compare the physical properties of the two kinds of (Ga,Mn)As:MnAs paramagnetic-ferromagnetic hybrids prepared either by MOVPE directly or by annealing of (Ga,Mn)As alloys grown by low-temperature MBE. The size and the density of MnAs clusters and the distance between them depends strongly on the growth and annealing parameters. The magnetic properties of clusters determined by ferromagnetic resonance measurements as well as the magneto-transport properties measured in the temperature range from 2 to 300 K in fields up to 10 T will be compared for hybrids fabricated by the two methods. The correlation between the magnetic properties of the ferromagnetic clusters and the paramagnetic matrix with the transport mechanisms will be discussed.