A. Stoffel and M. Gulácsi 2009 EPL 85 20009 doi:10.1209/0295-5075/85/20009
A. Stoffel and M. Gulácsi
Show affiliationsWe investigate the newly discovered supersolid phase by solving in random phase approximation the anisotropic Heisenberg model of the hard-core boson 4He lattice. We include nearest- and next-nearest-neighbor interactions and calculate exactly all pair correlation functions in a cumulant expansion scheme. Here we clarify the controversy over the role of the vacancies and defects, which have long been proposed to have a crucial role in the formation of a SS phase. We show that vacancies and interstitials will be present even at zero temperature in the supersolid phase. This phase is characterized by Bose condensation of the vacancies as well as the interstitials and may be regarded as a bond-ordered wave as it exhibits alternating strength of the expectation value of the kinetic energy term on bonds. We also show that the superfluid-to-supersolid transition is triggered by a collapsing roton minimum, however, the supersolid phase is stable against spontaneously induced superflow.
Issue 2 (January 2009)
Received 9 October 2008, accepted for publication 5 January 2009
Published 4 February 2009
A. Stoffel and M. Gulácsi 2009 EPL 85 20009
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