Numerical study of vortex matter using the Bose model: First-order melting and entanglement

TL;DR

This paper uses numerical simulations to study vortex matter, revealing a first-order melting transition into an entangled vortex liquid with properties consistent with experiments, and identifies a quantum phase transition in the boson model.

Contribution

It provides a detailed numerical analysis of vortex lattice melting and entanglement using the Bose model, including the first observation of a quantum phase transition in this context.

Findings

First-order vortex lattice melting transition observed.

The vortex liquid is denser than the lattice.

Identified a quantum phase transition from Wigner crystal to superfluid.

Abstract

We present an extensive numerical study of vortex matter using the mapping to 2D bosons and Path-Integral Monte Carlo simulations. We find a first-order vortex lattice melting transition into an entangled vortex liquid. The jumps in entropy and density are consistent with experimental results on YBCO. The liquid is denser than the lattice and has a correlation length l_z approx 1.7 epsilon a_0 in the direction parallel to the field. In the language of bosons we find a sharp quantum phase transition from a Wigner crystal to a superfluid, even in the case of logarithmic interaction. We also measure the excitation spectrum of the Bose system and find the roton minimum to be insensitive to the range of the interaction.