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Finite-temperature properties of frustrated classical spins coupled to the lattice

Cedric Weber·Federico Becca·Frederic Mila
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Abstract

We present extensive Monte Carlo simulations for a classical antiferromagnetic Heisenberg model with both nearest ($J_1$) and next-nearest ($J_2$) exchange couplings on the square lattice coupled to the lattice degrees of freedom. The Ising-like phase transition, that appears for $J_2/J_1>1/2$ in the pure spin model, is strengthened by the spin-lattice coupling, and is accompanied by a lattice deformation from a tetragonal symmetry to an orthorhombic one. Evidences that the universality class of the transition does not change with the inclusion of the spin-lattice coupling are reported. Implications for ${\rm Li_2VOSiO_4}$, the prototype for a layered $J_1{-}J_2$ model in the collinear regime, are also discussed.

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Cedric Weber, Federico Becca, Frederic Mila. 2005-03-03. Finite-temperature properties of frustrated classical spins coupled to the lattice. https://doi.org/10.1103/physrevb.72.024449

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