Superfluid-Insulator and Roughening Transitions in Domain Walls

TL;DR

This study uses quantum Monte Carlo simulations to explore superfluid-insulator and roughening transitions in domain walls of quantum lattice systems, revealing different behaviors in one and two dimensions.

Contribution

The paper provides the first detailed numerical analysis of superfluid and roughening transitions in domain walls within the hard-core Bose-Hubbard model.

Findings

In 1D, the transition is of the Kosterlitz-Thouless type with charge 1/2 quasiparticles.

In 2D, the transition belongs to the 3D U(1) universality class.

The interface remains superfluid over a wide interaction range before transitioning.

Abstract

We have performed quantum Monte Carlo simulations to investigate the superfluid behavior of one- and two-dimensional interfaces separating checkerboard solid domains. The system is described by the hard-core Bose-Hubbard Hamiltonian with nearest-neighbor interaction. In accordance with Ref.1, we find that (i) the interface remains superfluid in a wide range of interaction strength before it undergoes a superfluid-insulator transition; (ii) in one dimension, the transition is of the Kosterlitz-Thouless type and is accompanied by the roughening transition, driven by proliferation of charge 1/2 quasiparticles; (iii) in two dimensions, the transition belongs to the 3D U(1) universality class and the interface remains smooth. Similar phenomena are expected for domain walls in quantum antiferromagnets.