Magnetic-field-induced nonlocal effects on the vortex interactions in twin-free YBa2Cu3O7

TL;DR

This study investigates how magnetic fields influence vortex lattice structures in YBa2Cu3O7, revealing the increasing importance of anisotropy and nonlocal effects at higher fields and lower temperatures.

Contribution

The paper provides new neutron scattering data showing how anisotropy-induced nonlocal effects affect vortex lattice transitions in YBa2Cu3O7.

Findings

Nonlocal effects become more significant with increasing magnetic field.

Anisotropy influences vortex lattice structure and form factor.

Temperature approaching Tc suppresses nonlocal contributions.

Abstract

The vortex lattice (VL) in the high-kappa superconductor YBa2Cu3O7, at 2 K and with the magnetic field parallel to the crystal c-axis, undergoes a sequence of transitions between different structures as a function of applied magnetic field. However, from structural studies alone, it is not possible to determine precisely the system anisotropy that governs the transitions between different structures. To address this question, here we report new small-angle neutron scattering measurements of both the VL structure at higher temperatures, and the field- and temperature-dependence of the VL form factor. Our measurements demonstrate how the influence of anisotropy on the VL, which in theory can be parameterized as nonlocal corrections, becomes progressively important with increasing magnetic field, and suppressed by increasing the temperature towards Tc. The data indicate that nonlocality due to different anisotropies play important roles in determining the VL properties.