Regensburg 2010 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 15: Magnetic Half-metals and Oxides I

MA 15.8: Vortrag

Mittwoch, 24. März 2010, 12:00–12:15, H22

Origin of Ferrimagnetism in Ti and Cr doped α-Fe₂O₃ — •Hasan Sadat Nabi and Rossitza Pentcheva — Department of Earth and Environmental Sciences, University of Munich, Theresienstr. 41, 80333 Munich, Germany

Using density functional theory (DFT) and taking into account an on-site Coulomb repulsion term (GGA+U) we perform a comparative study of Ti and Cr substitution in α-Fe₂O₃. The charge mismatch in the FeTiO₃-Fe₂O₃ system is identified as a driving force towards ferrimagnetism as it leads to the formation of a mixed Fe²⁺, Fe³⁺ layer and uncompensated spins [1-2]. While a valence discontinuity is not present in the other system (Cr₂O₃-Fe₂O₃), we show that a different magnetic order and a net magnetization can be induced by controlling the concentration and arrangement of Cr ions in the Fe₂O₃-lattice, e.g. via heterostructuring. Furthermore the magnetic interaction parameters are extracted by mapping the DFT energies of different magnetic configurations to a Heisenberg Hamiltonian.

Funding by the DFG (Pe883/4-1) and ESF as well as the computational time at the Leibniz Rechenzentrum are gratefully acknowledged.

[1] R. Pentcheva and H. Sadat Nabi, Phys. Rev. B 77, 172405 (2008).

[2] H. Sadat Nabi and R. Pentcheva, J. Appl. Phys. 105, 053905 (2009).