Magnetic field-induced quasiparticle excitation in Nb3Sn: Evidence for anisotropic s-wave pairing

TL;DR

This study investigates the vortex state in Nb3Sn under magnetic fields, revealing a transition in vortex lattice structure and evidence for anisotropic s-wave pairing, advancing understanding of its electronic properties.

Contribution

It provides experimental evidence for anisotropic s-wave pairing in Nb3Sn using muon spin rotation and neutron scattering techniques, highlighting vortex structure transformation.

Findings

Vortex lattice transforms from hexagonal to square at 2-3 Tesla.

Magnetic penetration depth increases with field, indicating anisotropic pairing.

Evidence suggests Nb3Sn has anisotropic or multi-gapped s-wave superconductivity.

Abstract

The response of vortex state to the magnetic field in Nb3Sn is probed using muon spin rotation and small-angle neutron scattering. A transformation of vortex structure between hexagonal and squared lattice is observed over a relatively low field range of 2-3 Tesla. The gradual increase of the magnetic penetration depth with increasing field provides microscopic evidence for anisotropic (or multi-gapped) s-wave pairing suggested by the Raman scattering experiment. This result renders need for careful examination on the difference of electronic properties between Nb3Sn and V3Si.