A model of magnetic order in hexagonal HoMnO3

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.

9 pages, 3 figures

References in corpus (6)

• Giant magnetic anisotropy of the bulk antiferromagnets IrMn and IrMn3
• The nature of Ho magnetism in multiferroic HoMnO3
• Magnetic exchange interaction between rare-earth and Mn ions in multiferroic hexagonal manganites
• Theory of magnetic phases of hexagonal rare earth manganites
• Biquadratic antisymmetric exchange and the magnetic phase diagram of magnetoelectric CuFeO${}_2$
• Nonlocal Landau theory of the magnetic phase diagram of highly frustrated magnetoelectric CuFeO${}_2$

Cited by in corpus (1)

• Asymmetric splitting of an antiferromagnetic resonance via quartic exchange interactions in multiferroic hexagonal HoMnO${}_3$