# Spontaneous generation of fractional vortex-antivortex pairs at single edges of high-Tc superconductors

## TL;DR

This paper demonstrates that high-Tc superconductors with pair-breaking edges can spontaneously generate fractional vortex-antivortex pairs, leading to broken symmetries and observable zero-bias conductance peaks.

## Contribution

It shows that such symmetry-breaking phases can occur at any single pair-breaking edge, expanding the understanding of instability in unconventional superconductors.

## Key findings

- Presence of broad zero-energy density of states peak
- Spontaneous vortex-antivortex pairs at edges
- Implication for experimental zero-bias conductance peaks

## Abstract

Unconventional d-wave superconductors with pair-breaking edges are predicted to have ground states with spontaneously broken time-reversal and translational symmetries. We use the quasiclassical theory of superconductivity to demonstrate that such phases can exist at any single pair-breaking facet. This implies that a greater variety of systems, not necessarily mesoscopic in size, should be unstable to such symmetry breaking. The density of states averaged over the facet displays a broad peak centered at zero energy, which is consistent with experimental findings of a broad zero-bias conductance peak with a temperature-independent width at low temperatures.