arXiv:1903.04103 · Physical review. B./Physical review. B
Pair hopping in systems of strongly interacting hard-core bosons
Alvin J. R. Heng, Wenan Guo, Anders W. Sandvik, Pinaki Sengupta
Abstract
We have used the stochastic series expansion quantum Monte Carlo method to study interacting hard-core bosons on the square lattice with pair-hopping processes supplementing the standard single-particle hopping. Such pair hopping arises in effective models for frustrated quantum magnets. Our goal is to investigate the effects of the pair-hopping process on the commonly observed superfluid, insulating (Mott), and supersolid ground-state phases in the standard hard-core boson model with various interaction terms. The model is specifically motivated by the observation of finite dispersion of two-magnon bound states in neutron-diffraction experiments ${\mathrm{SrCu}}_{2}{({\mathrm{BO}}_{3})}_{2}$. Our results show that the pair hopping has different effects on Mott phases at different filling fractions, ``melting'' them at different critical pair-hopping amplitudes. Thus, it appears that pair hopping may play an important role in determining which out of a potentially large number of Mott phases (stabilized by details of the charge-diagonal interaction terms) actually survive the totality of quantum fluctuations present.