Commensurate lock-in and incommensurate supersolid phases of hard-core bosons on anisotropic triangular lattices

¹  Department of Physics, University of Toronto - Toronto, Ontario M5S 1A7, Canada
²  Department of Physics, National Tsing Hua University - Hsinchu, Taiwan 30013 ROC
³  Electrophysics Department, National Chiao Tung University - Hsinchu, Taiwan 300 ROC
⁴  Department of Physics, Tunghai University - Taichung, Taiwan 407 ROC
⁵  Theoretical Physics Division, Indian Association for the Cultivation of Sciences - Kolkata-700032, India

Received: 1 May 2009
Accepted: 24 July 2009

Abstract

We investigate the interplay between commensurate lock-in and incommensurate supersolid phases of the hard-core bosons at half-filling with anisotropic nearest-neighbor hopping and repulsive interactions on triangular lattice. We use numerical quantum and variational Monte Carlo as well as analytical Schwinger boson mean-field analysis to establish the ground states and phase diagram. It is shown that, for finite-size systems, there exist a series of jumps between different supersolid phases as the anisotropy parameter is changed. The density ordering wave vectors are locked to commensurate values and jump between adjacent supersolids. In the thermodynamic limit, however, the magnitude of these jumps vanishes leading to a continuous set of novel incommensurate supersolid phases.