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Spin correlations in an isotropic spin-5/2 two-dimensional antiferromagnet

R. L. Leheny·R. J. Christianson·R. J. Birgeneau·R. W. Erwin
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Abstract

We report a neutron scattering study of the spin correlations for the spin 5/2, two-dimensional antiferromagnet Rb_2MnF_4 in an external magnetic field. Choosing fields near the system's bicritical point, we tune the effective anisotropy in the spin interaction to zero, constructing an ideal S=5/2 Heisenberg system. The correlation length and structure factor amplitude are closely described by the semiclassical theory of Cuccoli et al. over a broad temperature range but show no indication of approaching the low-temperature renormalized classical regime of the quantum non-linear sigma model.

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R. L. Leheny, R. J. Christianson, R. J. Birgeneau, R. W. Erwin. 1998-09-11. Spin correlations in an isotropic spin-5/2 two-dimensional antiferromagnet. https://doi.org/10.1103/physrevlett.82.418

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