Interaction between superconductor and ferromagnetic domains in iron sheath: peak effect in MgB2/Fe wires

TL;DR

This paper investigates how the interaction between superconductor and ferromagnetic domains in MgB2/Fe wires causes a peak effect in critical current, highlighting the role of magnetic domain re-magnetization induced by the current's self-field.

Contribution

It proposes a new explanation for the peak effect in Ic(H) based on superconductor-magnetic domain interaction and re-magnetization of the iron sheath, which current models do not account for.

Findings

Peak effect in Ic(H) depends on magnetic domain re-magnetization.

A minimum critical current is required for the peak effect to occur.

Theoretical models need to incorporate superconductor-magnetic domain interactions.

Abstract

Interaction between the superconductor and ferromagnet in MgB2/Fe wires results in either a plateau or a peak effect in the field dependence of transport critical current, Ic(H). This is in addition to magnetic shielding of external field. Current theoretical models cannot account for the observed peak effect in Ic(H). This paper shows that the theoretical explanation of the peak effect should be sought in terms of interaction between superconductor and magnetic domain structure, obtained after re-magnetization of the iron sheath by the self-field of the current. There is a minimum value of critical current, below which the re-magnetization of the iron sheath and peak effect in Ic(H) are not observed.