We study the phase diagram of a two-dimensional assembly of bosons interacting via a soft-core repulsive pair potential of varying strength, and compare it to that of the equivalent system in which particles are regarded as distinguishable. We show that quantum-mechanical exchanges stabilize a ‘cluster crystal’ phase in a wider region of parameter space than predicted by calculations in which exchanges are neglected. This physical effect is diametrically opposite to that which takes place in hard-core Bose systems such as 4 He, wherein exchanges strengthen the fluid phase. This is underlain in the cluster crystal phase of soft-core bosons by the free energy gain associated with the formation of local Bose–Einstein condensates.
Exchange-induced crystallization of soft-core bosons / Cinti F.; Boninsegni M.; Pohl T.. - In: NEW JOURNAL OF PHYSICS. - ISSN 1367-2630. - ELETTRONICO. - 16:(2014), pp. 033038-033038. [10.1088/1367-2630/16/3/033038]
Exchange-induced crystallization of soft-core bosons
Cinti F.
Membro del Collaboration Group
;
2014
Abstract
We study the phase diagram of a two-dimensional assembly of bosons interacting via a soft-core repulsive pair potential of varying strength, and compare it to that of the equivalent system in which particles are regarded as distinguishable. We show that quantum-mechanical exchanges stabilize a ‘cluster crystal’ phase in a wider region of parameter space than predicted by calculations in which exchanges are neglected. This physical effect is diametrically opposite to that which takes place in hard-core Bose systems such as 4 He, wherein exchanges strengthen the fluid phase. This is underlain in the cluster crystal phase of soft-core bosons by the free energy gain associated with the formation of local Bose–Einstein condensates.File | Dimensione | Formato | |
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