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Suppression of antiferromagnetic correlations by quenched dipole--type impurities

V. Cherepanov·I. Ya. Korenblit·Amnon Aharony·O. Entin-Wohlman
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Abstract

The effect of quenched random ferromagnetic bonds on the antiferromagnetic correlation length of a two--dimensional Heisneberg model is studied, applying the renormalization group method to the classical non--linear sigma model with quenched random dipole moments. It is found that the antiferromagnetic long range order is destroyed for any non--zero concentration, of the dipolar defects, even at zero temperature. Below a line T ~ concentration, the correlation length is independent of T, and decreases exponentially with concentration. At higher temperatures, itdecays exponentially with an effective stiffness constant which decreases with concentration/T. The results are used to estimate the three--dimensional Néel temperature, which decays linearly with $x$ at small concentrations, and drops precipitously at a critical concentration. These predictions are compared with experiments on doped copper oxides, and are shown to reproduce successfully some of the prominent features of the data.

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V. Cherepanov, I. Ya. Korenblit, Amnon Aharony, O. Entin-Wohlman. 1998-08-21. Suppression of antiferromagnetic correlations by quenched dipole--type impurities. https://doi.org/10.1007/s100510050719

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