Is the pseudogap a topological state?

TL;DR

This paper proposes that the pseudogap in high-temperature superconductors is a topologically stable inhomogeneous condensate, specifically a lattice of skyrmions, explaining various experimental observations.

Contribution

It introduces a minimal order parameter theory interpreting the pseudogap as a topological state, unifying several experimental features under this framework.

Findings

Pseudogap modeled as a lattice of skyrmions

Explains time reversal symmetry breaking and checkerboard pattern

Inner magnetic fields are below experimental detection thresholds

Abstract

We conjecture that the pseudogap is an inhomogeneous condensate above the homogeneous state whose existence is granted by topological stability. We consider the simplest possible order parameter theory that provides this interpretation of the pseudogap and study its angular momentum states. The normal state gap density, the breaking of the time reversal symmetry and the checkerboard pattern are naturally explained under this view. The pseudogap is a lattice of skyrmions and the inner weak local magnetic field falls below the experimental threshold of observation given by NMR/NQR and $\mu$SR experiments.