Vortex glass transitions in disordered three-dimensional XY models: Simulations for several different sets of parameters

TL;DR

This study uses Monte Carlo simulations to investigate vortex glass transitions in disordered 3D XY models with varying anisotropy and magnetic fields, confirming previous findings and discussing the role of disorder strength.

Contribution

It provides detailed finite size scaling analysis of vortex glass transitions in anisotropic disordered XY models, highlighting the impact of anisotropy and disorder strength.

Findings

Helicity modulus analysis confirms previous results.

Strong anisotropy affects the scaling behavior.

Effective randomness influences the vortex glass transition.

Abstract

The anisotropic frustrated 3D XY model with strong disorder in the coupling constants is studied as a model of a disordered superconductor in an applied magnetic field. Simulations with the exchange Monte Carlo method are performed for frustrations f=1/5 and f=1/4, corresponding to two different values of the magnetic field along the z direction. The anisotropy is also varied. The determination of the helicity modulus from twist histograms is discussed in some detail and the helicity modulus is used in finite size scaling analyses of the vortex glass transition. The general picture is that the behavior in [Phys. Rev. Lett. 91, 077002 (2003)] is confirmed. For strong (e.g. isotropic) coupling in the z direction the helicity modulus fails to scale and it is argued that this is due to a too small effective randomness of such systems for the accessible system sizes.