title: Nematic order by thermal disorder in a three-dimensional lattice spin model with dipolarlike interactions.
abstract: At low temperatures, some lattice spin models with simple ferromagnetic or antiferromagnetic interactions (for example, nearest-neighbor interaction being isotropic in spin space on a bipartite three-dimensional lattice) produce orientationally ordered phases exhibiting nematic (second-rank) order, in addition to the primary first-rank one; on the other hand, in the literature, they have been rather seldom investigated in this respect. Here we study the thermodynamic properties of a three-dimensional model with dipolar-like interaction. Its ground state is found to exhibit full orientational order with respect to a suitably defined staggered magnetization (polarization), but no nematic second-rank order. Extensive Monte Carlo simulations, in conjunction with finite-size scaling analysis, have been used for characterizing its critical behavior; on the other hand, it has been found that nematic order does indeed set in at low temperatures, via a mechanism of order by disorder.
authors.affiliation: Institute of Solid State Physics, Bulgarian Academy of Sciences, 72 Tzarigradsko Chaussée, 1784 Sofia, Bulgaria.
authors.forename: Hassan
authors.initials: H
authors.lastname: Chamati
authors.affiliation: Physics Department, The University, via A. Bassi 6, 27100 Pavia, Italy.
authors.forename: Silvano
authors.initials: S
authors.lastname: Romano
mesh_terms: D003198:Computer Simulation; D055590:Electromagnetic Phenomena; D008962:Models, Theoretical; D009010:Monte Carlo Method; D013816:Thermodynamics