Abstract
There has been a rapidly growing interest in the interplay between spin-orbit coupling (SOC) and the Hubbard interaction in correlated materials. A current consensus is that the stronger the SOC, the smaller is the critical interaction required for a spin-orbit Mott insulator, because the atomic SOC splits a band into different total angular momentum bands, narrowing the effective bandwidth. It was further claimed that at large enough SOC, the stronger the SOC, the weaker the , because in general the effective SOC is enhanced with increasing electron-electron interaction strength. Contrary to this expectation, we find that, in orthorhombic perovskite oxides (Pbnm), the stronger the SOC, the bigger the . This originates from a line of Dirac nodes in bands near the Fermi level, inherited from a combination of the lattice structure and a large SOC. Due to this protected line of nodes, there are small hole and electron pockets in SrIrO, and such a small density of states makes the Hubbard interaction less efficient in building a magnetic insulator. The full phase diagram in vs SOC is obtained, where nonmagnetic semimetal, magnetic metal, and magnetic insulator are found. Magnetic ordering patterns beyond are also presented. We further discuss implications of our finding in relation to other perovskites such as SrRhO and SrRuO.
- Received 27 June 2012
DOI:https://doi.org/10.1103/PhysRevB.86.085149
©2012 American Physical Society