论文标题
v 3 $ d $充电和轨道状态在v $ _2 $ opo $ _4 $ x射线吸收光谱探测
V 3$d$ charge and orbital states in V$_2$OPO$_4$ probed by x-ray absorption spectroscopy
论文作者
论文摘要
v 3 $ d $电荷和轨道状态在v $ _2 $ opo $ _4 $中已通过X射线吸收光谱（XAS）进行了研究。 V $ _2 $ opo $ _4 $的电子结构非常独特，因为V $^{2+} $和V $^{3+}之间的电荷传输在面部共享vo $ _6 $链条中提供了负热扩展，如Pachoud {\ It et an。是。化学Soc。 {\ bf 140}，636（2018）。 V 2 $ p $ XAS线形状可以通过与V $^{2+} $和V $^{3+} $的混合价状态的多重计算复制。 O 1 $ S $和V 2 $ P $ XAS光谱的两极分化依赖性表示V 3 $ D $ ORBITAR订单，其中$ Xy $和$ Yz $（或$ ZX $）轨道在面部共享链中的V $^{3+} $处占据。被占用的$ xy $轨道对于V $^{2+} $与沿链条沿链条的V $^{2+} $与v $^{3+} $站点之间的反铁磁耦合至关重要，而被占用的$ yz $（或$ zx $）轨道的offermagnetic coupling在V $^$^$之间提供了抗fiferromagnetic coupling。
V 3$d$ charge and orbital states in V$_2$OPO$_4$ have been investigated by means of x-ray absorption spectroscopy (XAS). The electronic structure of V$_2$OPO$_4$ is very unique in that the charge transfer between V$^{2+}$ and V$^{3+}$ in face sharing VO$_6$ chains provides negative thermal expansion as reported by Pachoud {\it et al.} [J. Am. Chem. Soc. {\bf 140}, 636 (2018).] The near edge region of O 1$s$ XAS exhibits the three features which can be assigned to transitions to O 2$p$ mixed into the unoccupied V 3$d$ $t_{2g}$ and $e_{g}$ orbitals of V$^{2+}$ and V$^{3+}$. The V 2$p$ XAS line shape can be reproduced by multiplet calculations for a mixed valence state with V$^{2+}$ and V$^{3+}$. The polarization dependence of the O 1$s$ and V 2$p$ XAS spectra indicates V 3$d$ orbital order in which $xy$ and $yz$ (or $zx$) orbitals are occupied at the V$^{3+}$ site in the face sharing chains. The occupied $xy$ orbital is essential for the antiferromagnetic coupling between the V$^{2+}$ and V$^{3+}$ sites along the chains while the occupied $yz$ (or $zx$) orbital provides the antiferromagnetic coupling between the V$^{2+}$ and V$^{3+}$ sites between the chains.
