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MA: Magnetismus

MA 7: Spin-Elektronik

MA 7.5: Vortrag

Montag, 24. März 2003, 16:15–16:30, HSZ/401

Electronic structure, exchange interactions and Curie temperature in diluted III-V magnetic semiconductors: (GaCr)As, (GaMn)As, (GaFe)As. — •Leonid Sandratskii and Patrick Bruno — Max-Planck Institut für Mikrostrukturphysik, D-06120 Halle, German

We report the first-principles calculation of the electronic structure, exchange interactions and Curie temperature in diluted magnetic semiconductors (GaMn)As [1], (GaCr)As and (GaFe)As. Four concentrations of the 3d impurities are studied: 25%, 12.5%, 6.25%, 3.125%. (GaCr)As and (GaMn)As are found to possess a number of similar features. Both are semi-metallic and ferromagnetic, with similar properties of the interatomic exchange interactions and the same scale of the Curie temperature. In both systems the presence of the charge carriers is crucial for establishing the ferromagnetic order. An important difference between two systems is in the character of the dependence on the variation of the number of carriers. We find the exchange interactions between 3d atoms that make a major contribution into the ferromagnetism of (GaCr)As and (GaMn)As and propose an exchange path responsible for these interactions. The properties of (GaFe)As are found to differ crucially from the properties of (GaCr)As and (GaMn)As. (GaFe)As does not show a trend to ferromagnetism and is not half-metallic that makes this system unsuitable for the use in spintronic semiconductor devices.
1. L.M. Sandratskii and P. Bruno, Phys. Rev. B, 66, 134435 (2002)