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MA: Fachverband Magnetismus
MA 21: Magnetic Thin Films II
MA 21.1: Vortrag
Mittwoch, 27. Februar 2008, 14:00–14:15, H 1012
Exchange interactions and critical temperature of ultrathin films MnSi/Si(001) — •Mahbube Hortamani1,2, Leonid Sandratski1, Peter Kratzer3, Ingrid Mertig1,2, and Matthias Scheffler4 — 1MPI für Mikrostrukturphysik Halle — 2Martin-Luther-Universität Halle-Wittenberg — 3Universitaet Duisburg-Essen — 4FHI der MPG Berlin
Epitaxial growth of Mn on Si(001) has been recently studied in the context of spintronics, in order to investigate spin injection through a metal-semiconductor interface. Requirement for an efficient spin injection is to have a high spin polarization of carriers at the Fermi level which retains at room or higher temperature.
Earlier, we had shown that a well ordered layered structure of MnSi can be grown epitaxially on Si(001) substrate under Mn-rich conditions. These films were found to be ferromagnetic with the B2-type lattice structure. The spin moment of interfacial Mn atoms and the spin polarization at the Fermi level are considerable. In order to determine whether or not the thin films remain ferromagnetic above room temperature, we calculate the Curie temperature of ultrathin films MnSi/Si(001).
The Curie temperature is estimated within the multiple sublattice Heisenberg model, applying (i) a mean-field model and (ii) the random-phase approximation. The exchange coupling is obtained from energy differences of various collinear spin configurations. The calculations are performed using DFT with the GGA-PBE functional and the FP-APW+lo method, as implemented in the WIEN2k package.