Charge disproportionation in CaCu 3 Fe 4 O 12
Charge disproportionation in CaCu 3 Fe 4 O 12
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DOI：
10.1103/physrevb.79.113101
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发表时间：
2009-03
影响因子：
3.7
通讯作者：
X. Hao;Yuanhui Xu;F. Gao;Defeng Zhou;J. Meng
中科院分区：
文献类型：
--
作者：
X. Hao;Yuanhui Xu;F. Gao;Defeng Zhou;J. Meng
用WIEN2K程序实现的第一性原理计算方法研究了钙钛矿型${\text{CaCu}}_{3}{\text{Fe}}_{4}{\text{O}}_{12}$，的结构、电子和磁性，包括高温的$Im\TEXT{-}}3$和低温的$Pn\TEXT{-}}3$。高温相呈现均一价态和轨道简并的半金属行为，这与以前的理论结果一致。相反，Fe位上的轨道有序化、电荷有序化或歧化发生在低温相中，导致了绝缘性。更重要的是，电荷歧化是$2{d}^{5}L\ensuremath{\rightarrow}{d}^{5}{L}^{2}+{d}^{5}$类型的(其中$L$表示氧空穴或配体空穴)，并详细讨论了这一现象的起源。
First-principles calculations using the $\text{APW}+\text{lo}$ method, as implemented in the WIEN2K code, have been used to investigate the structural, electronic, and magnetic properties of the perovskite ${\text{CaCu}}_{3}{\text{Fe}}_{4}{\text{O}}_{12}$, including the high-temperature $Im\text{\ensuremath{-}}3$ and low-temperature $Pn\text{\ensuremath{-}}3$ phase. The high-temperature phase presents a homogeneous valence and an orbital degenerate half-metallic behavior, which is consistent with the previous theoretical result. Instead orbital ordering, charge ordering, or disproportionation on Fe sites occur in the low-temperature phase, leading to the insulating character. More importantly, the charge disproportionation is of $2{d}^{5}L\ensuremath{\rightarrow}{d}^{5}{L}^{2}+{d}^{5}$ type (where $L$ denotes an oxygen hole or a ligand hole), and the origin for the phenomenon is discussed in detail.