Pauli Paramagnetic Effects on Vortices in Superconducting TmNi2B2C

TL;DR

This study investigates how paramagnetic effects influence vortex structures in TmNi2B2C superconductors, combining experimental neutron scattering data with theoretical modeling to reveal field-dependent vortex form factors.

Contribution

It provides the first combined experimental and theoretical analysis of paramagnetic effects on vortex form factors in TmNi2B2C, including the role of exchange interactions with Tm moments.

Findings

Vortex form factor remains field independent up to 0.6 Hc2

A sharp decrease in form factor occurs at higher fields

Paramagnetic moments around vortex cores help maintain field contrast

Abstract

The magnetic field distribution around the vortices in TmNi2B2C in the paramagnetic phase was studied experimentally as well as theoretically. The vortex form factor, measured by small-angle neutron scattering, is found to be field independent up to 0.6 Hc2 followed by a sharp decrease at higher fields. The data are fitted well by solutions to the Eilenberger equations when paramagnetic effects due to the exchange interaction with the localized 4f Tm moments are included. The induced paramagnetic moments around the vortex cores act to maintain the field contrast probed by the form factor.