Quantum domain walls induce incommensurate supersolid phase on the anisotropic triangular lattice

TL;DR

This paper explores how quantum domain walls induce an incommensurate supersolid phase in an anisotropic triangular lattice Bose-Hubbard model, revealing a novel phase driven by topological defects and frustration effects.

Contribution

It introduces the concept of quantum domain walls leading to an incommensurate supersolid phase in an anisotropic lattice, supported by quantum Monte Carlo simulations.

Findings

Incommensurate supersolid phase emerges at intermediate anisotropy.

Structure factor peaks are linearly related to domain wall count.

Proliferation of quantum bosonic domain walls causes the phase transition.

Abstract

We investigate the extended hard-core Bose-Hubbard model on the triangular lattice as a function of spatial anisotropy with respect to both tunneling and nearest-neighbor interaction strength. At half-filling the system can be tuned from decoupled one-dimensional chains to a two-dimensional solid phase with alternating density order by adjusting the anisotropic coupling. At intermediate anisotropy, however, frustration effects dominate and an incommensurate supersolid phase emerges, which is characterized by incommensurate density order as well as an anisotropic superfluid density. We demonstrate that this intermediate phase results from the proliferation of topological defects in the form of quantum bosonic domain walls. Accordingly, the structure factor has peaks at wave vectors, which are linearly related to the number of domain walls in a finite system in agreement with extensive quantum Monte Carlo simulations. We discuss possible connections with the supersolid behavior in the high-temperature superconducting striped phase.