论文标题
多效性NII $ _2 $的现实旋转模型
Realistic Spin Model for Multiferroic NiI$_2$
论文作者
论文摘要
使用对称适应的群集扩展方法，为II型多效性NII $ _2 $构建了现实的基于原则的自旋汉密尔顿。除了单离子各向异性和各向同性的海森堡术语外，该模型还包括Kitaev的相互作用和二次化术语，并且可以很好地复制实验性螺旋基态的引人注目的特征，即{\ it，例如，例如，例如，适当的螺钉状态，旋转平面，旋转平面，传播方向和周期。使用此模型来构建相图，证明（i）$ \ langle1 \ bar10 \ rangle $的平面内传播方向是由Kitaev交互确定的，而不是长期存在的交换挫败感； （ii）旋转平面的倾斜也主要通过Kitaev相互作用而不是层间耦合来确定。此外，其他蒙特卡洛模拟显示了三个等效的域和不同的拓扑缺陷。由于II型多型旋转中的旋转诱导了铁电性，因此我们的工作也意味着Kitaev的相互作用与NII $ _2 $的多效性密切相关。
A realistic first-principle-based spin Hamiltonian is constructed for the type-II multiferroic NiI$_2$, using a symmetry-adapted cluster expansion method. Besides single ion anisotropy and isotropic Heisenberg terms, this model further includes the Kitaev interaction and a biquadratic term, and can well reproduce striking features of the experimental helical ground state, that are, {\it e.g.}, a proper screw state, canting of rotation plane, propagation direction and period. Using this model to build a phase diagram, it is demonstrated that, (i) the in-plane propagation direction of $\langle1\bar10\rangle$ is determined by the Kitaev interaction, instead of the long-believed exchange frustrations; and (ii) the canting of rotation plane is also dominantly determined by Kitaev interaction, rather than interlayer couplings. Furthermore, additional Monte Carlo simulations reveal three equivalent domains and different topological defects. Since the ferroelectricity is induced by spins in type-II multiferroics, our work also implies that Kitaev interaction is closely related to the multiferroicity of NiI$_2$.
