Two-dimensional superfluidity and localization in the hard-core boson model: A quantum Monte Carlo study.

Quantum Monte Carlo simulations are used to investigate the twodimensional superfluid properties of the hard-core boson model, which show a strong dependence on particle density and disorder. We obtain further evidence that a half-filled clean system becomes superfluid via a finite temperature Kosterlitz-Thouless transition. The relationship between low temperature superfluid density and particle density is symmetric and appears parabolic about the half filling point. Disorder appears to break the superfluid phase up into two distinct localized states, depending on the particle density. We find that these results strongly correlate with the results of several experiments on high-Tc superconductors. PACS numbers: 74.20.Mn, 05.70.Jk, 72.15.Rn, 74.76.Bz Submitted to Phys. Rev. Lett., June 3, 1993 Transferred/Resubmitted to Phys. Rev. B, December 21, 1993 Accepted for publication in Phys. Rev. B, December 30, 1993 Typeset using REVTEX