Eur. Phys. J. B 67, 169-181 (2009)
https://doi.org/10.1140/epjb/e2009-00018-6

Finite temperature properties of a supersolid: a RPA approach

¹ Max-Planck-Institute for the Physics of Complex Systems, 01187 Dresden, Germany
² Nonlinear Physics Centre, Australian National University, Canberra, ACT, 0200, Australia

Corresponding author: ^a ajs105@rsphyse.anu.edu.au

Received: 14 October 2008
Revised: 16 December 2008
Published online: 20 January 2009

Abstract

We study in random-phase approximation the newly discovered supersolid phase of ⁴He and present in detail its finite temperature properties. ⁴He is described within a hard-core quantum lattice gas model, with nearest and next-nearest neighbour interactions taken into account. We rigorously calculate all pair correlation functions in a cumulant decoupling scheme. Our results support the importance of the vacancies in the supersolid phase. We show that in a supersolid the net vacancy density remains constant as function of temperature, contrary to the thermal activation theory. We also analyzed in detail the thermodynamic properties of a supersolid, calculated the jump in the specific heat which compares well to the recent experiments.