Relativistic magnetic effects in 4d-5d transition metal oxides

  • Cao, Gang (PI)

Grants and Contracts Details


The 4d and 5d transition metal oxides have been a fertile ground for new physics and the subject of substantial renewed interest in the last decade as the physical properties of these materials are qualitatively different from the 3d counterparts intensively studied before. A considerable spin-orbit coupling and much larger spatial extent of the 4d and 5d wave functions (as compared to 3d) strongly influence electronic and magnetic properties of these compounds, which leads to possibility of such exotic effects as spin liquid phases, unusual topological phases, orbital-selective spin-singlet states, interplay of itinerant and localized magnetism, magnetic exitons, the multipolar exchange interaction etc. In the present project we will perform theoretical and experimental investigation of some of these phenomena, including, but not limited to the excitonic magnetism and formation of orbital-selective spin-singlet states in the 4d and 5d transition metal compounds, with a focus on double perovskite and low-dimensional (dimer, trimers, chains) structures. In particular, one of the challenges is to understand and explain a mysterious recent observation of a finite magnetic moment in the formally closed-shell Ir5+ ions in some double perovskites. Another goal is to assess the possibility of formation of ferromagnetic states (so far not observed, but theoretically conducive) in double perovskites. For the theoretical study (Russian and first American teams) we will use a combination of density functional (DFT) and dynamical mean-field theories (DMFT), which allows accurate treatment of the details of the band structure of real materials, while taking into account many-body electron correlations. The experimental part of the project (the second American team) includes synthesis and characterization of single crystals of novel 4d and 5d transition metal compounds and measurements of structural, magnetic, thermal, transport and dielectric properties. The synergy in collaboration between high-level theoretical and experimental groups will allow us to gain insight into the interplay between the strong Coulomb correlations, itineracy, spin-orbit coupling and dimensionality of particular 4d and 5d transition metal compounds.
Effective start/end date3/1/158/31/16


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