Magnetically-driven orbital-selective insulator-metal transition in double perovskite oxides
Abstract
Interaction-driven metal-insulator transitions or Mott transitions are widely observed in condensed-matter systems. In multi-orbital systems, many-body physics is richer in which an orbital-selective metal-insulator transition is an intriguing and unique phenomenon. Here we use first-principles calculations to show that a magnetic transition (from paramagnetic to long-range magnetically ordered) can simultaneously induce an orbital-selective insulator-metal transition in rock-salt ordered double perovskite oxides A2BB'O6 where B is a non-magnetic ion (Y3+ and Sc3+) and B' a magnetic ion with a d3 electronic configuration (Ru5+ and Os5+). The orbital selectivity originates from geometrical frustration of a face-centered-cubic lattice on which the magnetic ions B' reside. Including realistic structural distortions and spin-orbit interaction do not affect the transition. The predicted orbital-selective transition naturally explains the anomaly observed in the electric resistivity of Sr2YRuO6. Implications of other available experimental data are also discussed. Our work shows that by exploiting geometrical frustration on non-bipartite lattices, novel electronic/magnetic/orbital-coupled phase transitions can occur in correlated materials that are in the vicinity of metal-insulator phase boundary.