Department of Physics and Physical Oceanography, Memorial University, St John's, NF, A1B 3X7, Canada.
J Phys Condens Matter. 2010 Apr 28;22(16):162201. doi: 10.1088/0953-8984/22/16/162201. Epub 2010 Mar 30.
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 the onset of Ho magnetic order. On the basis of 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.
利用对称原理，我们为 HoMnO(3) 复杂磁序的描述建立了一个自旋哈密顿模型。通过对 AB 堆叠三角反铁磁体中受困 Mn 离子模型的 Landau-Lifshitz-Gilbert 动态扭矩方程的全新应用，证明了在该模型中观察到的四个主要自旋组态是稳定的。Ho-Mn 耦合是由于一个不寻常的三角各向异性项，它负责 Mn 自旋重新定向和 Ho 磁有序的开始。基于这些微观考虑，我们推导出一个平均场 Landau 型自由能，它再现了在零场下观察到的一系列温度驱动的磁相变，包括再入行为。此外，我们的分析表明，基面磁有序应该与晶格略有失谐。
