Bose soft disks: a minimal model for supersolidity

Sebastiano Saccani (1) , Saverio Moroni (2) , Ettore Vitali (3) , Massimo Boninsegni (4)

1 SISSA / ISAS - Scuola Internazionale Superiore di Studi Avanzati / International School for Advanced Studies
2 IOM-CNR
3 UNIMI - Università degli Studi di Milano = University of Milan
4 University of Alberta

The low temperature phase diagram of an assembly of Bose particles, interacting via a simple soft disk potential, is studied numerically by means of Monte Carlo simulations. At sufficiently high densities, the system features a cluster crystal phase, as observed in its classical counterpart. In the low temperature limit, and in a relatively wide region of parameter space, the quantum cluster crystal undergoes a transition to a supersolid phase, displaying both a finite superfluid fraction and crystalline order. We argue that soft-core Bosons ought be regarded as a ''minimal model'' of continuous-space supersolidity. With the aim of elucidating the interplay between superfluid response and solid order, we compute the excitation spectrum of the system. A comparison of that of the insulating cluster crystal with that of the supersolid, shows that the latter features an additional acoustic mode.

Mots clés: Physical Sciences

Domaines: Matière Condensée [cond-mat]

Sebastiano Saccani, Saverio Moroni, Ettore Vitali, Massimo Boninsegni. Bose soft disks: a minimal model for supersolidity. Molecular Physics, 2012, 109 (23-24), pp.2807-2812. ⟨10.1080/00268976.2011.615346⟩. ⟨hal-00771583⟩