Orbital-selective Mott-insulator transition in Ca 2 - x Sr x RuO 4 |
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Authors: | V.I. Anisimov I.A. Nekrasov D.E. Kondakov T.M. Rice M. Sigrist |
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Affiliation: | Russian Academy of Sciences-Ural Division, Institute of Metal Physics, Yekaterinburg GSP-170, 620219, Russia Theoretische Physik, ETH-H?nggerberg 8093, Zürich, Switzerland
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Abstract: | The electronic structures of the metallic and insulating phases of the alloy series Ca2-xSrxRuO4 ( 0 ? x ? 2) are calculated using LDA, LDA+U and Dynamical Mean-Field Approximation methods. In the end members the groundstate respectively is an orbitally non-degenerate antiferromagnetic insulator (x = 0) and a good metal (x = 2). For x > 0.5 the observed Curie-Weiss paramagnetic metallic state which possesses a local moment with the unexpected spin S = 1/2, is explained by the coexistence of localized and itinerant Ru-4d-orbitals. For 0.2 < x < 0.5 we propose a state with partial orbital and spin ordering. An effective model for the localized orbital and spin degrees of freedom is discussed. The metal-insulator transition at x = 0.2 is attributed to a switch in the orbital occupation associated with a structural change of the crystal. Received 27 July 2001 |
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Keywords: | PACS. 75.30.-m Intrinsic properties of magnetically ordered materials – 75.50.-y Studies of specific magnetic materials |
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