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
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.
PACS: 05.30.Jp – Boson systems / 67.80.-s – Quantum solids / 67.80.bd – Superfluidity in solid 4He, supersolid 4He / 75.10.Jm – Quantized spin models
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2009