Theory of resonant x-ray scattering and the establishment of the ab initio calculation method of the associated excited states

X射线共振散射理论及相关激发态从头计算方法的建立

• 批准号: 14540323
• 负责人: IGARASHI Jun-ichi
• 金额: $ 0.9万
• 依托单位: Japan Atomic Energy Research Institute
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2002
• 资助国家: 日本
• 起止时间: 2002 至 2003
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-14540323/
• 关键词: resonant x-ray scattering (RXS); resonant inelastic scattering (RIXS); K absorption edge; orbital order; magnetic order; 4p electronic state; spin-orbit interaction; 共鳴X線散乱; 磁気円二色性; 格子歪

We have studied the mechanism of the resonant x-ray scattering (RXS) from the microscopic viewpoint, and have obtained the following results :Elastic scattering(1)We have analyzed the RXS spectra at the magnetic superlattice spots around the Cu K edge in the antiferromagnet KCuF_3 and around the Ni K edge in NiO. Taking account of the spin-orbit interaction, we have carried out ab initio calculations within the local density approximation. We have explained various experimental facts, having clarified the mechanism of the orbital polarization on the zip band.(2)We have analyzed the RXS spectra at the magnetic superlattice spots around the Ga K edge in the antiferromagnet UGa_3 by carrying out the ab initio calculation with taking account of the spin-orbit interaction. We have clarified tha mechanism that the large orbital polarization in the 4p band of UGa3 arises from the large orbital moment of U atoms through the mixing between the Ga 4p states and the U 5f states. The experimental … More large spectral intensitieshave been explained naturally by the analysis.(3)We have analyzed the RXS spectra at the quadrupole ordering superlattice spots in CeB_6 on the basis of an atomic model including Ce4f-Ce4f interatomic interaction. The interference between the resonant scattering and the Thomson scattering found in the experiment have been well reproduced without assuming the lattice distortion.Inelastic scattering(1)We have analyzed the resonant inelastic scattering (RIXS) spectra around the Ge K edge on the basis of the ab initio calculation. The experimental spectra have been well reproduced, and the relation between the spectra and the band mapping has been clarified.(2)We have analyzed the RIXS spectra around the Cu K edge in La_2CuO_4 on the basis of the d-p model. Using the Hartree-Fock approximation together with the random phase approximation, we have calculated the spectra in good agreement with the experiment. We have clarified the mechanism for the move of the the spectral peak with varying final-state momenta. Less

我们从微观角度研究了X射线共振散射（RXS）的机理，并得到了以下结果：弹性散射（1）我们分析了Cu K边缘周围磁超晶格斑点处的RXS谱。考虑到自旋轨道相互作用，我们在局域密度近似内进行了从头计算。 (2)通过从头计算,考虑反铁磁体UGa_3中Ga K边缘磁超晶格点处的RXS谱,分析了反铁磁体UGa_3中Ga K边缘磁超晶格点的RXS谱。我们阐明了 UGa3 4p 能带中大轨道极化是由 U 原子之间的混合产生的大轨道矩产生的机制。 Ga 4p态和U 5f态的实验结果已经通过分析得到了自然的解释。(3)我们基于包括Ce4f的原子模型分析了CeB_6中四极有序超晶格点的RXS光谱。 -Ce4f原子间相互作用，在不假设晶格的情况下，很好地再现了实验中发现的共振散射和汤姆逊散射之间的干涉。非弹性散射(1)我们在从头计算的基础上分析了Ge K边缘周围的共振非弹性散射(RIXS)光谱，很好地再现了实验光谱，并且得到了光谱与能带映射之间的关系。 (2)基于d-p模型,利用Hartree-Fock分析了La_2CuO_4中Cu K边的RIXS谱。近似与随机相位近似一起，我们计算出的光谱与实验非常吻合，我们已经阐明了光谱峰随不同终态动量的移动机制。

项目成果

M.Usuda, M.Takahashi, J.Igarashi: "An Ab-Initio Calculation of Magnetic Resonant X-Ray Scattering Spectra in NiO"Phys.Rev.B. 69. 014408(1)-014408(7) (2004)

M.Usuda、M.Takahashi、J.Igarashi：“NiO 中磁共振 X 射线散射光谱的从头算”Phys.Rev.B。

T.Nagao, J.Igarashi: "Interference between Thomson Scattering and Resonant Scattering in X-Ray Diffraction from CeB_6"J.Phys.Soc.Jpn.. 72-9. 2381-2384 (2003)

T.Nagao、J.Igarashi：“来自 CeB_6 的 X 射线衍射中汤姆逊散射和共振散射之间的干涉”J.Phys.Soc.Jpn.. 72-9。

M.Usuda: "An Ab-Initio Calculation of Magnetic Resonant X-Ray Scattering Spectra in NiO"Physical Review B. 69. 014408(1)-014408(7) (2004)

M.Usuda：“NiO 中磁共振 X 射线散射光谱的从头计算”物理评论 B. 69. 014408(1)-014408(7) (2004)

T.Nagao: "Interference between Thomson Scattering and Resonant Scattering in X-Ray Diffraction from CeB_6"J.Phys.Soc.Jpn.. 72. 2381-2384 (2003)

T.Nagao：“来自 CeB_6 的 X 射线衍射中汤姆逊散射和共振散射之间的干涉”J.Phys.Soc.Jpn.. 72. 2381-2384 (2003)

Y.Nishikawa: "Resonant Inelastic X-Ray Scattering at the K Edge of Ge"J.Phys.Soc.Jpn.. (掲載予定). (2004)

Y.Nishikawa：“Ge K 边缘处的共振非弹性 X 射线散射”J.Phys.Soc.Jpn..（待出版）。