Electronic properties of emergent topological defects in chiral $p$-wave superconductivity

TL;DR

This paper explores the electronic properties of complex topological defects in chiral p-wave superconductors, revealing unique local density of states features and their potential for experimental detection.

Contribution

It provides a self-consistent microscopic analysis of exotic topological defects, including skyrmions, in chiral p-wave superconductors, linking their structure to observable electronic signatures.

Findings

Skyrmions contain closed chiral domain walls mapped by zero-bias LDOS peaks

LDOS shows electron-hole asymmetry distinct from conventional vortices

Skyrmions can be large, stable, and pinned, aiding experimental detection

Abstract

Chiral $p$-wave superconductors in applied magnetic field can exhibit more complex topological defects than just conventional superconducting vortices, due to the two-component order parameter (OP) and the broken time-reversal symmetry. We investigate the electronic properties of those exotic states, some of which contain clusters of one-component vortices in chiral components of the OP and/or exhibit skyrmionic character in the \textit{relative} OP space, all obtained as a self-consistent solution of the microscopic Bogoliubov-de Gennes equations. We reveal the link between the local density of states (LDOS) of the novel topological states and the behavior of the chiral domain wall between the OP components, enabling direct identification of those states in scanning tunneling microscopy. For example, a skyrmion always contains a closed chiral domain wall, which is found to be mapped exactly by zero-bias peaks in LDOS. Moreover, the LDOS exhibits electron-hole asymmetry, which is different from the LDOS of conventional vortex states with the same vorticity. Finally, we present the magnetic field and temperature dependence of the properties of a skyrmion, indicating that this topological defect can be surprisingly large in size, and can be pinned by an artificially indented non-superconducting closed path in the sample. These features are expected to facilitate the experimental observation of skyrmionic states, thereby enabling experimental verification of chirality in emerging superconducting materials.