The influence of twin boundaries on the Flux Line Lattice structure in YBaCuO: a study by Small Angle Neutron Scattering

TL;DR

This study investigates how twin boundaries in YBaCuO superconductors influence the flux line lattice structure using Small Angle Neutron Scattering, revealing significant modifications and potential links to increased critical current.

Contribution

It provides new insights into the impact of twin boundaries on flux line lattice structures and their relation to superconducting properties in YBaCuO.

Findings

Twin boundaries strongly modify the FLL structure.

Flux lines meander with the magnetic field angle.

Two different FLL unit cells are observed depending on conditions.

Abstract

The influence of Twin Boundaries (TB) on the Flux Line Lattice(FLL) structure was investigated by Small Angle Neutron Scattering (SANS). YBaCuO single crystals possessing different TB densities were studied. The SANS experiments show that the TB strongly modify the structure of the FLL. The flux lines meander as soon as the magnetic field makes an angle with the TB direction. According to the value of this angle but also to the ratio of the flux lines density over the TB density, one observes that the FLL exhibits two different unit cells in the plane perpendicular to the magnetic field. One is the classical hexagonal and anisotropic cell while the other is affected by an additional deformation induced by the TB. We discuss a possible relation between this deformation and the increase of the critical current usually observed in heavily twinned samples.