Magneto-topological transitions in multicomponent superconductors

TL;DR

This paper explores how magnetic flux can induce transitions between chiral and time-reversal symmetric states in multicomponent superconductors, revealing magneto-topological effects in mesoscopic cylinders.

Contribution

It demonstrates flux-driven transitions between chiral and symmetric states in multiband superconductors using a Ginzburg-Landau model, highlighting magneto-topological effects.

Findings

Magnetic flux can switch chiral $s_{ ext{pm}}+is_{++}$ states to $s_{ ext{pm}}$ states.

Flux tuning affects energy splitting of inequivalent pairing amplitudes.

Transitions can be detected via signatures in mesoscopic superconducting loops.

Abstract

Multi-component spin-singlet superconductors with competing 0- and $\pi$-pairing couplings, as in $s_{++}$ and $s_{\pm}$ phases, are close to instabilities with a spontaneous breaking of time-reversal symmetry. We demonstrate that the modification of the kinetic energy of superconducting electrons in a doubly connected superconducting cylinder, determined by the applied flux, generally drives transitions from chiral superconducting states to configurations that are time-reversal symmetric. This magneto-topological-induced changeover is investigated by means of a Ginzburg-Landau approach for a two-band superconductor with interband interactions and impurity scattering investigated for the case of a sample in the form of a mesoscopically thin-walled cylinder. We find that the application of a magnetic flux can convert a chiral $s_{\pm}+is_{++}$ state into a $s_{\pm}$ configuration and vice versa or tune the energy splitting of chiral states having inequivalent pairing amplitudes. We discuss signatures for the detection of these phases and of the corresponding transitions in mesoscopic superconducting loops.