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arXiv · 1202.2321

A model of magnetic order in hexagonal HoMnO3

S. G. Condran·M. L. Plumer
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Abstract

Symmetry arguments are used to develop a spin Hamiltonian for the description of the complex magnetic ordering in HoMnO$_3$. Using a novel application of the Landau Lifshitz Gilbert dynamic torque equations to this model of the frustrated Mn ions on an $AB$ stacked triangular antiferromagnetic, it is shown that the four principal spin configurations observed in this compound are stabilized. Ho-Mn coupling is found to be a consequence of an unusual trigonal anisotropy term which is responsible for simultaneous Mn spin reorientation and onset of Ho magnetic order. Based on these microscopic considerations, a mean-field Landau-type free energy is derived which reproduces the succession of observed temperature driven magnetic phase transitions at zero field, including re-entrant behavior. In addition, our analysis suggests that the basal-plane magnetic order should be slightly incommensurate with the lattice.

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S. G. Condran, M. L. Plumer. 2012-02-10. A model of magnetic order in hexagonal HoMnO3. https://doi.org/10.1088/0953-8984%2F22%2F16%2F162201

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