Instability towards Staggered Loop Currents in the Three-Orbital Model for Cuprate Superconductors

TL;DR

This paper provides evidence for a new type of orbital current instability in cuprates, suggesting a staggered loop-current pattern that could explain pseudogap phenomena and related experimental observations.

Contribution

It identifies a novel staggered pattern of loop currents in a multiorbital Hubbard model, differing from previous intra-unit cell current proposals.

Findings

Staggered loop-current pattern causes Fermi surface reconstruction.

The pattern induces a pseudogap with time-reversal symmetry breaking.

Potentially explains charge order and Kerr effect in cuprates.

Abstract

We present evidence for the existence of a spontaneous instability towards an orbital loop-current phase in a multiorbital Hubbard model for the CuO$_2$ planes in cuprates. Contrary to the previously proposed $\theta_{II}$ phase with intra-unit cell currents, the identified instability is towards a staggered pattern of intertwined current loops. The orbitally resolved current pattern thereby shares its staggered character with the proposal of d-density wave order. The current pattern will cause a Fermi surface reconstruction and the opening of a pseudogap. We argue that the pseudogap phase with time-reversal symmetry breaking currents is susceptible to further phase transitions and therefore offers a route to account for axial incommensurate charge order and a polar Kerr effect in underdoped cuprates.