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

TL;DR

This paper models Sr2IrO4 using a twisted Hubbard model to explain its magnetic properties and suggests that doping could lead to high-temperature superconductivity, drawing parallels with cuprates.

Contribution

It introduces a SU(2) invariant pseudospin-1/2 Hubbard model with a twisted coupling for Sr2IrO4, providing a new theoretical framework for its magnetic behavior and superconductivity potential.

Findings

The model explains the magnetic anisotropy and ferromagnetism in Sr2IrO4.

Doping Sr2IrO4 may induce high-temperature superconductivity.

The approach offers testable predictions for future experiments.

Abstract

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 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.