Berlin 2012 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 35: Magnetic Heusler Compounds I
MA 35.2: Vortrag
Mittwoch, 28. März 2012, 15:30–15:45, H 0112
Ab initio investigation of Co2FeSi1−xZx and Co2Fe1−xZ1+x Heusler alloys: Magnetism and tetragonal instability — •Heike C. Herper and Peter Entel — Faculty of Physics and CeNIDE, University of Duisburg-Essen, 47048 Duisburg, Germany
Since the magnetic properties of Heusler compounds can be relatively easily controlled by composition these alloys seem to be suitable for different magnetic applications, e.g., in magnetoelectronic and magnetocaloric devices and one can think of multifunctional devices. Here, we present an ab initio study of Co2FeSi1−xZx and Co2Fe1−xZ1+x Heusler alloys with Z = Al, Sb, Sn. Electronic properties have been studied within the density functional theory using the VASP and SPRKKR code. Information about finite temperature properties is obtained from Monte Carlo simulations of the classical Heisenberg model with ab initio determined exchange coupling constants.
We have investigated the composition dependence of the magnetic transition temperatures and the spin polarization which are important for spintronic applications as well as the tendencies of martensitic phase transformation. Replacing Si in Co2FeSi partially by Fe the cubic phase is preferred and spin polarization remains large, whereas, Si excess stabilizes the tetragonal phase, but spin polarization is drastically reduced. However, if fractions of Si are replaced by Sb the system also exhibits a tetragonal instability, but with reasonable large spin polarization.
This work is financially supported through the Deutsche Forschungsgemeinschaft (SFB 491).