Orbital physics in ruthenates: First-principles studies

Abstract

In this review, we concentrate on the orbital physics in ruthenates. Two issues will be addressed. One is related to the spin/orbital ordering in Ca 2-xSr xRuO 4. Based on detailed first-principles calculations, we will discuss the crucial role of orbital degree of freedom and its relationship to structure distortions and magnetic properties. The orbital-dependent magnetic phase control in Ca 2-xSr xRuO 4 will be illustrated. The second issue is concerned with the electronic state and quantum transport in the presence of the spin order, namely the anomalous Hall effect (AHE) in ferromagnetic Ca 1-xSr xRuO 3. By detailed first-principles calculations and comparison with experimental result, we provide firm evidence for the intrinsic mechanism of AHE due to the existence of Berry phase in the presence of spin-orbital coupling, which is entirely topological. © IOP Publishing Ltd and Deutsche Physikalische Gesellschaft.