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Classical heisenberg antiferromagnet away from the pyrochlore lattice limit: entropic versus energetic selection

C. Pinettes·B. Canals·C. Lacroix
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Abstract

The stability of the disordered ground state of the classical Heisenberg pyrochlore antiferromagnet is studied within extensive Monte Carlo simulations by introducing an additional exchange interaction $J'$ that interpolates between the pyrochlore lattice ($J'=0$) and the face-centered cubic lattice ($J'=J$). It is found that for $J'/J$ as low as $J'/J\ge 0.01$, the system is long range ordered : the disordered ground state of the pyrochlore antiferromagnet is unstable when introducing very small deviations from the pure $J'=0$ limit. Furthermore, it is found that the selected phase is a collinear state energetically greater than the incommensurate phase suggested by a mean field analysis. To our knowledge this is the first example where entropic selection prevails over the energetic one.

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C. Pinettes, B. Canals, C. Lacroix. 2002-02-12. Classical heisenberg antiferromagnet away from the pyrochlore lattice limit: entropic versus energetic selection. https://doi.org/10.1103/physrevb.66.024422

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