Based on a microscopic theoretical study, we show that novel superconductivity is induced by carrier doping in layered perovskite Ir oxides where a strong spin-orbit coupling causes an effective total angular momentum Jeff=1/2 Mott insulator. Using a variational Monte Carlo method, we find an unconventional superconducting state in the ground state phase diagram of a t2g three-orbital Hubbard model on the square lattice. This superconducting state is characterized by a dx2-y2-wave "pseudospin singlet" formed by the Jeff=1/2 Kramers doublet, which thus contains interorbital as well as both singlet and triplet components of t2g electrons. The superconducting state is found stable only by electron doping, but not by hole doping, for the case of carrier doped Sr2IrO4. We also study an effective single-orbital Hubbard model to discuss the similarities to high-Tc cuprate superconductors and the multiorbital effects.
ASJC Scopus subject areas
- Physics and Astronomy(all)