Crystal electric field ofP2-NaxCoO2for the intermediate spin state of Co3+
Crystal electric field ofP2-NaxCoO2for the intermediate spin state of Co3+
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Co3中间自旋态P2-NaxCoO2晶体电场
DOI：
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发表时间：
2013
期刊：
影响因子：
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通讯作者：
F. Chou
中科院分区：
文献类型：
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作者：
G. Shu;F. Chou
在新提出的八面体晶体电场（CEF）修改下，重新审视并检查了居里-韦斯金属体系中 P2（γ）型 NaxCoO2 的每 Co4+ 磁矩。所提出的模型通过分裂eg和t2g基团之间窄间隙的类激子基本激发解释了Co3+中间态S=1存在的起源。 CoO2 层建议由具有链间耦合的倾斜边缘共享方形平面 CoO2 链构建。 CoO2 的方形平面 CEF 需要 Co 与四个面内相邻氧原子之间形成共价键，而位于相邻链中的氧原子可被视为 CoO6 伪八面体的低有效电荷的顶端氧原子。角分辨光电子能谱 (ARPES) 未能观察到 kz=0 处的局域密度近似 (LDA) 预测的空穴以及 LDA 和 CEF 计算之间 t2g 分裂的相反顺序的原因也可以使用所提出的模型来解决。
The magnetic moment per Co4+ of P2(gamma)-type NaxCoO2 in Curie-Weiss metal regime is revisited and examined under a newly proposed modification of the octahedral crystal electric field (CEF). The proposed model explains the origin of the existence of the intermediate state S=1 for Co3+ through an exciton-like elementary excitation of the narrow gap between the split eg and t2g groups. The CoO2 layer is proposed to be constructed from the tilted edge-sharing square-planar CoO2 chains with inter-chain coupling. The square-planar CEF of CoO2 requires covalent bond formation between Co and the four in-plane neighboring oxygens, while the oxygens sitting in the neighboring chains can be viewed as apical oxygens of low effective charge for a CoO6 pseudo-octahedron. The reason why angle-resolved photoemission spectroscopy (ARPES) failed to observe the local-density approximation (LDA) predicted e'g hole pockets at kz=0 and the reversed order of the t2g splittings between LDA and CEF calculations can also be resolved using the proposed model.