ACTA

Interplay Between Spin-Orbit Coupling and Structural Deformations in Heavy Transition-Metal Oxides with Tetrahedral Coordination

F. Forte^a,b, D. Guerra^a, A. Avella^a,b,c, C. Autieri^d, A. Romano^a,b, C. Noce^a,b
^aDipartimento di Fisica "E.R. Caianiello", Università degli Studi di Salerno, I-84084 Fisciano (SA), Italy
^bCNR-SPIN, UOS di Salerno, I-84084 Fisciano (SA), Italy
^cUnità CNISM di Salerno, Università degli Studi di Salerno, I-84084 Fisciano (SA), Italy
^dCNR-SPIN, UOS L'Aquila, Sede Temporanea di Chieti, 66100 Chieti, Italy

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We analyze the effects of a large spin-orbit coupling on the magnetic state of a d¹ transition-metal ion located in a tetrahedral environment. While in the ideal tetrahedral symmetry the spin-orbit coupling acts only as a perturbation on the atomic energy levels set by the crystal-field splitting, we demonstrate that its effects are strongly enhanced in the case of distorted geometries. In particular, we consider the specific case in which the tetrahedron is compressed along the z direction, and show that, by increasing the degree of flattening, a large spin-orbit interaction (i) can induce a substantial anisotropic, unquenched orbital momentum and (ii) can affect the hierarchy of the lowest energy levels that are involved in the magnetic exchange.

DOI: 10.12693/APhysPolA.133.394
PACS numbers: 71.70.Ej, 75.25.Dk, 71.27.+a