Vortices and 2D bosons: A Path-Integral Monte Carlo Study

TL;DR

This study uses path-integral Monte Carlo simulations to analyze vortex behavior in high-temperature superconductors, revealing a first-order transition from an ordered lattice to a superfluid vortex liquid with specific thermodynamic properties.

Contribution

It provides the first numerical evidence of a first-order vortex lattice melting transition in high-T_c superconductors using a mapping to 2D bosons and path-integral Monte Carlo.

Findings

First-order transition from Abrikosov lattice to vortex liquid

Entropy jump of 0.4 k_B per vortex and layer

Vortex liquid exhibits bosonic superfluidity

Abstract

The vortex system in a high-T_c superconductor has been studied numerically using the mapping to 2D bosons and the path-integral Monte Carlo method. We find a single first-order transition from an Abrikosov lattice to an entangled vortex liquid. The transition is characterized by an entropy jump dS = 0.4 k_B per vortex and layer (parameters for YBCO) and a Lindemann number c_L = 0.25. The increase in density at melting is given by d\rho = 6.0*10^{-4} / \lambda(T)^2. The vortex liquid corresponds to a bosonic superfluid, with \rho_s = \rho even in the limit \lambda -> \infty.