title: Phase separation in supersolids
abstract: We study quantum phase transitions in the ground state of the two dimensional hard-core boson Hubbard Hamiltonian. Recent work on this and related models has suggested "supersolid" phases with simultaneous diagonal and off-diagonal long range order. We show numerically that, contrary to the generally held belief, the most commonly discussed "checkerboard" supersolid is thermodynamically unstable. Furthermore, this supersolid cannot be stabilized by next-near-neighbor interaction. We obtain the correct phase diagram using the Maxwell construction. We demonstrate that the "striped" supersolid is thermodynamically stable and is separated from the superfluid phase by a continuous phase transition.
authors.affiliation: Institut Non-Lineaire de Nice, Universite de Nice-Sophia Antipolis, 1361 route des Lucioles, 06560 Valbonne, France.
authors.initials: GG
authors.lastname: Batrouni
authors.initials: RT
authors.lastname: Scalettar