Orbital currents in extended Hubbard models of high-T$_c$ cuprates

TL;DR

This paper explores conditions under which orbital currents can be stabilized in extended Hubbard models of high-Tc cuprates, linking theoretical models to recent experimental observations of broken time-reversal symmetry.

Contribution

It demonstrates that orbital currents can develop in extended Hubbard models with oxygen orbitals, especially when additional interactions like apical oxygen hybridization are considered.

Findings

Orbital currents develop on finite clusters.

Currents are stabilized in the thermodynamic limit with additional interactions.

Hybridization with apical oxygens enhances current stability.

Abstract

Motivated by the recent report of broken time-reversal symmetry and zero momentum magnetic scattering in underdoped cuprates, we investigate under which circumstances orbital currents circulating inside a unit cell might be stabilized in extended Hubbard models that explicitly include oxygen orbitals. Using Gutzwiller projected variational wave functions that treat on an equal footing all instabilities, we show that orbital currents indeed develop on finite clusters, and that they are stabilized in the thermodynamic limit if additional interactions, e.g. strong hybridization with apical oxygens, are included in the model.