Superfluidity versus localization of two-dimensional hard-core boson model: a quantum Monte Carlo study

Abstract

Quantum Monte Carlo simulations are used to investigate two-dimensional superfluidity of the hard-core boson model, that depends on particle density and disorder. It is definitely found that the clean system at half filling becomes superfluid via finite temperature Kosterlitz-Thouless transition. The low temperature superfluid density, as a function of particle density, displays a symmetric and parabolic shape about half filling. Disorder alters the superfluid phase into two distinct localized phases, depending on particle density. The universal relationship between T c and carrier-density, as experimentally reported for high-T c superconductors, appears to correlate with the computational result.