Giant paramagnetic Meissner effect in multiband superconductors

TL;DR

This paper demonstrates that multiband superconductors can exhibit a giant paramagnetic Meissner effect, significantly larger than the diamagnetic response, due to complex vortex interactions and flux configurations.

Contribution

It reveals the existence of a giant paramagnetic response in multiband superconductors, linked to the crossover between Type-I and Type-II behavior, a novel phenomenon not previously observed.

Findings

Giant paramagnetic response observed in multiband superconductors.

Paramagnetic response exceeds diamagnetic Meissner response.

Flux configurations are locked by surface effects.

Abstract

Superconductors, ideally diamagnetic when in the Meissner state, can also exhibit paramagnetic behavior due to trapped magnetic flux. In the absence of pinning such paramagnetic response is weak, and ceases with increasing sample thickness. Here we show that in multiband superconductors paramagnetic response can be observed even in slab geometries, and can be far larger than any previous estimate - even multiply larger than the diamagnetic Meissner response for the same applied magnetic field. We link the appearance of this giant paramagnetic response to the broad crossover between conventional Type-I and Type-II superconductors, where Abrikosov vortices interact non-monotonically and multibody effects become important, causing unique flux configurations and their locking in the presence of surfaces.