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Phys. Rev. B 34, 4710–4718 (1986)

[Issue 7 – October 1986 ]

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Lattice distortions and short-range magnetic order in classical magnetoelastic Heisenberg chains

M. Marchand, A. Caillé, and R. Pépin

Département de Physique et Centre de Recherche en Physique du Solide, Université de Sherbrooke, Sherbrooke, Québec J1K 2R1, Canada

Lattice distortions of a two-dimensional array of one-dimensional classical Heisenberg spin chains with magnetoelastic coupling are studied in the limit of strong interchain elastic interactions. Exact integration over the spin degrees of freedom leads to a temperature-dependent free-energy functional of the elastic variables only. The equilibrium lattice structure is obtained from the ground state of this free-energy functional and the phase diagram indicates the presence of a tricritical point. The necessity of performing the calculations at constant pressure is stressed and it is shown that a dimerized phase could be reached by applying pressure to certain magnetic materials, provided that there exist positive second-neighbor elastic interactions. The consequences of lattice distortions on the short-range magnetic order are studied by calculating the wave-number-dependent magnetic susceptibility. It is found that the dominant short-range magnetic order is of period four in the dimerized lattice phase.

©1986 The American Physical Society

URL: http://publish.aps.org/abstract/PRB/v34/p4710
PACS: 75.10.Hk

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References

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