Fractional vortices and Ising superconductivity in multiband superconductors

TL;DR

This paper theoretically explores multiband 2D superconductors, revealing how interband couplings influence vortex states and how Ising-type spin-orbit coupling enhances in-plane critical fields, inspired by recent experiments.

Contribution

It provides new insights into vortex bound states and the role of Ising spin-orbit coupling in multiband superconductors, connecting theory with recent experimental findings.

Findings

Vortex bound states exhibit spatial anisotropy linked to interband couplings.

Ising-type spin-orbit coupling enhances in-plane upper critical fields.

Theoretical predictions align with recent experimental observations.

Abstract

Inspired by the recent experiments in monolayer iron-based superconductors, we theoretically investigate properties of a two-dimensional multiband superconductor, focusing on two aspects. First, for vortex bound states, the spatial anisotropy and positions of electron density peaks are associated with interband couplings. Second, even with inversion symmetry, there allows a Ising-type spin-orbit coupling, leading to the enhanced in-plane upper critical field.