Twisted Hubbard model for Sr2IrO4: magnetism and possible high temperature superconductivity

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Materials

Background:

• Strontium iridate (Sr2IrO4) is characterized as a Mott insulator with a single J(eff)=1/2 band, analogous to cuprates.
• Observed large magnetic anisotropy and ferromagnetism in Sr2IrO4 complicate the simple Mott insulator picture.

Purpose of the Study:

• To propose a theoretical model for the low-energy electronic structure of Sr2IrO4.
• To explain the observed magnetic properties of Sr2IrO4.
• To explore the potential for high-temperature superconductivity in doped Sr2IrO4.

Main Methods:

• Mapping the electronic structure of Sr2IrO4 to a pseudospin-1/2 space.
• Utilizing a SU(2) invariant pseudospin-1/2 Hubbard model.
• Analyzing the coupling to an external magnetic field via a g tensor with staggered antisymmetric components.

Main Results:

• The low-energy electronic structure of Sr2IrO4 is accurately described by a Hubbard model similar to cuprates.
• The proposed model naturally explains the complex magnetic properties, including anisotropy and ferromagnetism.
• Several testable predictions for future experiments on Sr2IrO4 were derived.

Conclusions:

• Sr2IrO4's electronic and magnetic properties can be understood through a pseudospin-1/2 Hubbard model with specific magnetic field coupling.
• Electron-doping Sr2IrO4 presents a promising avenue for achieving high-temperature superconductivity.