Dresden 2006 – scientific programme

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MA: Magnetismus

MA 11: Spin-Structures and Magnetic Phase Transitions II

MA 11.2: Talk

Monday, March 27, 2006, 15:15–15:30, HSZ 403

Helimagnetsm and metamagnetic transitions in novel bulk GMR alloys based on MnAu2. — •Sergii Khmelevskyi, Laslo Udvardi, Laslo Szunyogh, Peter Mohn, and Peter Weinberger — Center for Computational Material Science, Vienna University of Technology, Getreidemarkt 5/134, A-1060 Vienna, Austria

Magnetic exchange interactions in helimagnetic MnAu2 compound and their dependence upon alloying with Fe and Cr are studied from first principles using General Perturbation Method within Surface Korringa-Kohn-Rostoker formalism for band structure calculations. The calculated interactions well reproduce the results of neutron diffraction experiments concerning periodicity of the helix in MnAu2 and its weakening with Fe substitution, providing background for conventional model interpretations of metamagnetic processes in this systems responsible for Giant Magneto-Resistance effect. However, for (Mn,Cr)Au2, alloys our results reveal entirely different picture suggesting that experimentally observed magnetization process in the Cr doped alloys may follows a scenario predicted theoretically few decades ago for nearly orthogonal helimagnetics.