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Mott-insulator transition in Ca(2-x)Sr(x)RuO4: A study of the electronic and magnetic properties

V. I. Anisimov·I. A. Nekrasov·D. E. Kondakov·T. M. Rice·M. Sigrist
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Abstract

The electronic structures of the metallic and insulating phases of the alloy series Ca(2-x)Sr(x)RuO4 (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.

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V. I. Anisimov, I. A. Nekrasov, D. E. Kondakov, T. M. Rice, M. Sigrist. 2001-07-04. Mott-insulator transition in Ca(2-x)Sr(x)RuO4: A study of the electronic and magnetic properties. https://arxiv.org/abs/cond-mat/0107095

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