Phys. Rev. B 42, 10360–10380 (1990)Exact theories of m-component quadrupolar systems showing a first-order phase transitionReceived 27 August 1990; published in the issue dated 1 December 1990 Several statistical-thermodynamic theories involving an exact solution in one dimension (d=1), high- and low-temperature series expansions, and an exact solution of an infinite-range system (mean-field theory) are presented for a quadrupolar spin model whose Hamiltonian is described with m-component classical spins Si as scrH=-1/2 tsumi,j=1N Jij(Si⋅Sj)2 on a d-dimensional lattice. An orientational phase transition is analyzed systematically as a function of m. The transition is first order generally for 2<m≤∞ and d>2. We evaluate the transition point and the discontinuity in energy as a function of m. We also present exact solutions in the m→∞ limit for arbitrary spatial dimensions. © 1990 The American Physical Society URL:
http://link.aps.org/doi/10.1103/PhysRevB.42.10360
DOI:
10.1103/PhysRevB.42.10360
PACS:
64.60.Cn, 64.70.Md
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