Orbital polarization, charge transfer, and fluorescence in reduced-valence nickelates
Orbital polarization, charge transfer, and fluorescence in reduced-valence nickelates
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DOI：
10.1103/physrevb.107.165124
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发表时间：
2023-04-12
影响因子：
3.7
通讯作者：
Dean，M. P. M.
中科院分区：
文献类型：
--
作者：
Norman，M. R.;Botana，A. S.;Dean，M. P. M.
本文提出了一种计算 X 射线吸收 (XAS) 和共振非弹性 X 射线散射 (RIXS) 的简单形式，其输入来自单粒子或多体初始计算的轨道分辨态密度，旨在捕获类似巡回的特征。我们使用这种形式通过密度泛函理论 (DFT) 和最近研究的还原价镍酸盐的输入来计算 XAS 和 RIXS，然后将这些结果与铜酸盐和未还原镍酸盐的结果进行对比。与未还原的相比，还原价的镍酸盐和铜酸盐由于未占据态的轨道占主导地位而表现出强烈的轨道极化。我们还重现了最近 RIXS 实验的两个关键方面：（i）氧态之间的电荷转移特征，我们发现其能量随着从铜酸盐到铜酸盐的变化而降低，以及（ii）由未占据态与态杂交产生的荧光线的能量依赖性偏振反转。最后，我们得出了我们的结果对还原价镍酸盐中电子性质的一些影响。
This paper presents a simple formalism for calculating x-ray absorption (XAS) and resonant inelastic x-ray scattering (RIXS) that has as input orbital-resolved density of states from a single-particle or many-bodyab initiocalculation and is designed to capture itinerant like features. We use this formalism to calculate both the XAS and RIXS with input from density functional theory (DFT) andfor the recently studied reduced valence nickelatesand(), and these results are then contrasted with those for the cuprateand the unreduced nickelate. In contrast to the unreduced, the reduced valence nickelates as well as the cuprate show strong orbital polarization due to the dominance oforbitals for the unoccupiedstates. We also reproduce two key aspects of a recent RIXS experiment for: (i) a charge-transfer feature betweenand oxygenstates whose energy we find to decrease as one goes fromtoto the cuprate, and (ii) an energy-dependent polarization reversal of the fluorescence line that arises from hybridization of the unoccupiedstates withstates. We end with some implications of our results for the nature of theelectrons in reduced valence nickelates.