Magnetic response of mesoscopic superconducting rings with two order parameters

TL;DR

This study investigates the magnetic behavior of mesoscopic aluminum superconducting rings with two order parameters, revealing metastable states and phase locking phenomena predicted by a two-parameter Ginzburg-Landau model.

Contribution

It provides experimental evidence for metastable states and fractional vortices in two-order-parameter superconducting rings, confirming theoretical predictions.

Findings

Metastable states with different phase windings observed

Fractional vortices analogous states identified

Phase locking increases with coupling strength

Abstract

The magnetic response and fluxoid transitions of superconducting aluminum rings of various sizes, deposited under conditions likely to generate a layered structure, show good agreement with a two-order-parameter Ginzburg-Landau model. For intermediate couplings, we find metastable states that have different phase winding numbers around the ring in each of the two order parameters. Those states, previously theoretically predicted, are analogous to fractional vortices in singly connected samples with two-order-parameter superconductivity. Larger coupling locks the relative phase so that the two order parameters are only manifest in the temperature dependence of the response. With increasing proximitization, this signature gradually disappears.