Magnetooptical activity of spinel type crystals with complex mixed-valence lattice irregularities |
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Authors: | Lubov Falkovskaya Boris Tsukerblat |
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Institution: | a Institute of Metal Physics, Ural Branch of Russian Academy of Sciences, 18, S. Kovalevskaya Str., 620041 Ekaterinburg, Russia b Institute of Metallurgy, Ural Branch of Russian Academy of Sciences, 101, Amundsen Str., 620016 Ekaterinburg, Russia c Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel |
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Abstract: | In this Letter we analyze the peculiarities of the Faraday rotation in the imperfect spinel type crystals for which the lattice irregularities are represented by the mixed valence clusters of transition metal ions. A such kind of complex system with the electronic configuration (for example, Mn2+ Mn2+ Mn3+) is considered in detail. The model takes into account the cubic and low symmetry crystal fields acting on the metal ions, migration of the “extra” hole as well as the orientational degeneracy (hidden optical anisotropy). The electric dipole transitions in these types of clusters with migrating hole coupled to the spin core through the double exchange mechanism are shown to lead to a significant magnetooptical activity in the visible range of spectrum. The intensity of these transitions can be comparable or higher than those for the magnetic dipole ones in the same range of frequencies. The electric dipole mechanism of the magnetooptical effects manifests itself in a highly anisotropic character of the spectra. |
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Keywords: | Magnetooptical activity Faraday rotation Mixed valence Double exchange Transition metal clusters Crystal field |
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