论文标题
j = 0 k $ _2 $ os $ x_6 $（x = f，cl和br）中的非磁性绝缘状态
J = 0 nonmagnetic insulating state in K$_2$Os$X_6$ (X = F, Cl and Br)
论文作者
论文摘要
在$ 4D/5D $过渡金属系统中，许多有趣的物理特性来自带宽，电子相关性和自旋轨道相互作用的相互作用。在这里，使用{\ it Ab intib}密度函数理论，我们系统地研究了双层类样系统K $ _2 $ _2 $ os $ x_6 $（x = f，cl和br），具有$ 5D^4 $电子配置。我们的主要结果是$ J = 0 $非磁性绝缘状态在该系统中形成，这是由强旋轨道耦合引起的。具体而言，分离良好的OS $ x_6 $ octahedra导致了立方晶体场限制，并导致最近的邻居OS-OS站点中的跳跃大幅下降。在这种情况下，将三个退化$ t_ {2g} $ orbital重建为两个``'' $ j _ {\ rm eff} = 3/2 $轨道。此外，OS $ 5D $轨道与$ x $（$ x $ = f，cl和br）$ p $轨道之间的杂交增加了从f到br，在k $ _2 $ _2 $ _2 $ _2 $ _6 $中引导电子的本地化，比k $ _2 $ _6 $ _6 $ _6 $ _6 $ _6 $ _2 $ _2 $ _2 $ _2 $ _2 $ _2 K $ _2 $ OSF $ _6 $比CL-或BR-情况。我们的结果为实验者和理论家提供了指导，从事这一有趣的osmium卤化家庭。
In $4d/5d$ transition-metal systems, many interesting physical properties arise from the interplay of bandwidth, electronic correlations, and spin-orbit interactions. Here, using {\it ab initio} density functional theory, we systematically study the double-perovskite-like system K$_2$Os$X_6$ (X = F, Cl, and Br) with a $5d^4$ electronic configuration. Our main result is that the $J = 0$ nonmagnetic insulating state develops in this system, induced by strong spin-orbital coupling. Specifically, the well-separated Os$X_6$ octahedra lead to the cubic crystal-field limit and result in dramatically decreasing hoppings in nearest neighbor Os-Os sites. In this case, the three degenerate $t_{2g}$ orbitals are reconstructed into two ``effective'' $j_{\rm eff}$ ($j_{\rm eff} = 1/2$ and $j_{\rm eff} = 3/2$ states) states separated by the strong SOC, opening a gap with four electrons occupying the $j_{\rm eff} = 3/2$ orbitals. Furthermore, the hybridization between the Os $5d$ orbitals and the $X$ ($X$ = F, Cl, and Br) $p$ orbitals increases from F to Br, leading the electrons in K$_2$OsF$_6$ to be more localized than in K$_2$OsCl$_6$ and K$_2$OsBr$_6$, resulting in a smaller bandwidth for K$_2$OsF$_6$ than in the Cl- or Br- cases. Our results provide guidance to experimentalists and theorists working on this interesting family of osmium halides.
