Berlin 2008 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 30: Electron Theory

MA 30.8: Vortrag

Donnerstag, 28. Februar 2008, 16:15–16:30, H 1028

Electronic and magnetic properties of Fe₃O₄ in the electronic ground state and in a constrained excited state — •Christos Kostoglou, Reinhard Singer, and Manfred Fähnle — Max-Planck-Institut für Metallforschung, Heisenbergstr. 3, 70569 Stuttgart

Below the Verwey temperature T_V magnetite (Fe₃O₄) exhibits an insulating, ordered phase with a special type of charge, spin and orbital order [1,2] due to an ordered arrangement of two types of atoms Fe(B,1) and Fe(B,2) on the Fe(B) sublattice. For an interpretation of experiments on the electronic conductivity and on the magnetic aftereffect at finite temperatures below T_V it is generally assumed [3] that there are thermally-activated electronic transitions involving pairs of exchanged Fe(B,1) and Fe(B,2) atoms as intermediate configuration. The energy difference between the perfectly ordered state and the state containing such a defect is calculated by the LDA+U method and the augmented spherical wave method.

[1] I. Leonov, A.N. Yaresko, V.N. Antonov, M.A. Korotin, and V.I. Anisimov, Phys. Rev. Lett. 93, 146404 (2004)

[2] Horng-Tay Jeng, G.Y. Guo, and D.J. Huang, Phys. Rev. Lett. 93, 156403 (2004)

[3] F. Walz, J. Phys.: Condens. Matter 14, R285 (2002), M. Fähnle, H. Kronmüller, F. Walz, Physica B 369, 177-180 (2005)