Topological phase transitions in small mesoscopic chiral p-wave superconductors

TL;DR

This paper investigates the phase diagram of small mesoscopic chiral p-wave superconductors, revealing the emergence of topological domain walls and their interaction with edge states as the system size increases.

Contribution

It provides a microscopic self-consistent analysis of phase transitions and domain wall formations in mesoscopic chiral p-wave superconductors, highlighting topological defects.

Findings

Giant vortex states dominate in ultra-small samples.

Domain walls form and break symmetry as size increases.

Two types of domain walls interact differently with edge states.

Abstract

Spin-triplet chiral p-wave superconductivity is typically described by a two-component order parameter, and as such is prone to unique emergent effects when compared to the standard single-component superconductors. Here we present the equilibrium phase diagram for small mesoscopic chiral p-wave superconducting disks in the presence of magnetic field, obtained by solving the microscopic Bogoliubov-de Gennes equations self-consistently. In the ultra-small limit, the cylindrically-symmetric giant-vortex states are the ground state of the system. However, with increasing sample size, the cylindrical symmetry is broken as the two components of the order parameter segregate into domains, and the number of fragmented domain walls between them characterizes the resulting states. Such domain walls are topological defects unique for the p-wave order, and constitute a dominant phase in the mesoscopic regime. Moreover, we find two possible types of domain walls, identified by their chirality-dependent interaction with the edge states.