Regensburg 2007 – scientific programme

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MA: Fachverband Magnetismus

MA 13: Spinstructures and magnetic Phase Transitions

MA 13.1: Talk

Tuesday, March 27, 2007, 10:15–10:30, H5

First-principles description of phase transitions in transition-metal compounds. — •Leonid Sandratskii — Max-Planck-Institut für Mikrostrukturphysik, Halle, Germany

We calculate interatomic exchange parameters in hexagonal MnAs and orthorhombic MnAs. The magnetic transition temperatures are estimated within the mean-field and random-phase approximations. The results of the calculations are used to interpret the unusual sequence of the phase transitions in the system. The limitations of the Heisenberg-Hamiltonian description of the hexagonal MnAs are revealed and interpreted. The importance of the adequate choice of the magnetic degrees of freedom is demonstrated. We obtain strong difference in the properties of hexagonal MnAs and half-metallic Heusler compound NiMnSb.