Direct evidence for an intrinsic square vortex lattice in the overdoped high-Tc superconductor La1.83Sr0.17CuO4+d

TL;DR

This study provides the first direct evidence of an intrinsic square vortex lattice in a high-Tc superconductor, revealing a field-dependent transition from triangular to square vortex arrangements, linked to anisotropic properties.

Contribution

It reports the first direct observation of a square vortex lattice in a high-Tc superconductor, highlighting the role of anisotropy in vortex lattice structure.

Findings

Observation of a well ordered vortex lattice in La1.83Sr0.17CuO4+d

Crossover from triangular to square vortex coordination with increasing magnetic field

Intrinsic square vortex lattice linked to anisotropic effects

Abstract

We report here the first direct observations of a well ordered vortex lattice in the bulk of a La(2-x)Sr(x)CuO(4+d) (La214) single crystal (slightly overdoped, x=0.17). Our small angle neutron scattering investigation of the mixed phase reveals a crossover from triangular to square coordination with increasing magnetic field. The existence of an intrinsic square vortex lattice has never been observed in high-temperature superconductors (HTSC), and is indicative of the coupling of the vortex lattice to a source of anisotropy, such as those provided by a d-wave order parameter or the presence of stripes.