论文标题
Kitaev候选材料中的旋转相互作用和磁性
Spin interaction and magnetism in cobaltate Kitaev candidate materials: an $ab$ $initio$ and model Hamiltonian approach
论文作者
论文摘要
为了寻求托管Kitaev自旋液体的材料，许多努力都集中在第四和第五轮过渡金属化合物上，它们是自旋轨道耦合辅助莫特绝缘子。在这里，我们研究了3 $ d $过渡金属氧化物的结构和磁性特性，NA $ _2 $ _2 $ _2 $ teo $ _6 $和na $ _3 $ co $ _2 $ _2 $ sbo $ _6 $。钠在以前的化合物中的部分占用率是使用簇扩展来解决的，并且发现钠的蜂窝状晶格在能量方面受到了青睐。从\ textIt {ab intio}带结构开始，多体二阶扰动理论导致伪杂种 - $ \ frac {1} {2} {2} $ hamiltonian具有估计的磁相互作用。我们表明，仅当第一个邻居基塔耶（Kitaev）耦合在海森伯格（Heisenberg）术语中占主导地位时，实验观察到的锯齿形磁态才能稳定，这两个偶联由于存在$ e_g $ orbitals而受到高度抑制。在这两种化合物中都发现了第三个邻居海森堡的互动占主导地位。我们还提出了一个NA $ _2 $ CO $ _2 $ _2 $ _6 $的相图，通过改变电子电子和自旋轨道相互作用。发现计算出的自旋激发光谱可捕获最近实验木元光谱的基本特征，并为我们的结果提供了贷款支持。
In the quest for materials hosting Kitaev spin liquids, much of the efforts have been focused on the fourth- and fifth-row transition metal compounds, which are spin-orbit coupling assisted Mott insulators. Here, we study the structural and magnetic properties of 3$d$ transition metal oxides, Na$_2$Co$_2$TeO$_6$ and Na$_3$Co$_2$SbO$_6$. The partial occupancy of sodium in former compound is addressed using a cluster expansion, and a honeycomb lattice of sodiums is found to be energetically favored. Starting from the \textit{ab initio} band structures, a many-body second order perturbation theory leads to a pseudospin-$\frac{1}{2}$ Hamiltonian with estimated magnetic interactions. We show that the experimentally observed zigzag magnetic state is stabilized only when the first neighbor Kitaev coupling dominates over the Heisenberg term, both of which are highly suppressed due to presence of $e_g$ orbitals. A third neighbor Heisenberg interaction is found dominant in both these compounds. We also present a phase diagram for Na$_2$Co$_2$TeO$_6$ by varying the electron-electron and spin-orbit interactions. The computed spin excitation spectra are found to capture essential features of recent experimental magnon spectrum, lending support to our results.
