paper

Ising transition in the two-dimensional quantum Heisenberg model

arXiv:cond-mat/0312050 · doi:10.1103/PhysRevLett.92.157202

Abstract

We study the thermodynamics of the spin- two-dimensional quantum Heisenberg antiferromagnet on the square lattice with nearest () and next-nearest () neighbor couplings in its collinear phase (), using the pure-quantum self-consistent harmonic approximation. Our results show the persistence of a finite-temperature Ising phase transition for every value of the spin, provided that the ratio is greater than a critical value corresponding to the onset of collinear long-range order at zero temperature. We also calculate the spin- and temperature-dependence of the collinear susceptibility and correlation length, and we discuss our results in light of the experiments on LiVOSiO and related compounds.

4 page, 4 figures

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