An Interpretation of the Neutron Scattering Data on Flux Lattices of Superconductors

TL;DR

This paper analyzes neutron scattering data on flux lattices in superconductors using a generalized free energy method, revealing symmetry breaking and complex phase behavior in vortex lattices.

Contribution

It introduces a generalized one-field effective free energy approach to interpret neutron diffraction data on flux lattices, highlighting symmetry breaking and phase richness.

Findings

Fourfold crystal symmetry is explicitly broken.

Vortex lattice becomes oblique, not rectangular.

Rich phase diagram of flux lattices is described.

Abstract

Small angle neutron diffraction experiments are analyzed using recently developed and properly generalized one-field effective free energy method. In the case of experiment of Keimer et al on YBCO, we show that the fourfold symmetry of the underlying crystal is explicitly broken, but the reflection with respect to the [110] and [1\={1}0] axes remains a symmetry. The vortex lattice also becomes generally oblique instead of rectangular body centered. Unexpectedly rich phase diagram is described.