Twisted Hubbard Model for Sr2IrO4: Magnetism and Possible High Temperature Superconductivity

Sr2IrO4 has been suggested as a Mott insulator from a single J(eff) 1/2 band, similar to the cuprates. However, this picture is complicated by the measured large magnetic anisotropy and ferromagnetism. Based on a careful mapping to the J(eff) = 1/2 (pseudospin-1/2) space, we propose that the low energy electronic structure of Sr2IrO4 can indeed be described by a SU(2) invariant pseudospin-1/2 Hubbard model very similar to that of the cuprates, but with a twisted coupling to an external magnetic field (a g tensor with a staggered antisymmetric component). This perspective naturally explains the magnetic properties of Sr2IrO4. We also derive several simple facts based on this mapping and the known results about the Hubbard model and the cuprates, which may be tested in future experiments on Sr2IrO4. In particular, we propose that (electron-) doping Sr2IrO4 can potentially realize high-temperature superconductivity.