Crystal structure and charge-ordering in La1.5Ca0.5CoO4 studied by neutron and resonant X-ray scattering

被引：23

作者：

Horigane, Kazumasa ^{[1
]}

Nakao, Hironori ^{[2
]}

Kousaka, Yusuke ^{[1
]}

Murata, Tetsuya ^{[2
]}

Noda, Yukio ^{[3
]}

Murakami, Youichi ^{[2
]}

Akimitsu, Jun ^{[1
]}

机构：

[1] Aoyama Gakuin Univ, Dept Math & Phys, Kanagawa 2298558, Japan

[2] Tohoku Univ, Dept Phys, Sendai, Miyagi 9808578, Japan

[3] Tohoku Univ, Inst Multidisciplinary Res Adv Mat, Sendai, Miyagi 9808577, Japan

来源：

JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN | 2008年 / 77卷 / 04期

关键词：

cobalt oxides; checkerboard charge ordering; intermediate spin state; neutron scattering; resonant x-ray scattering;

D O I：

10.1143/JPSJ.77.044601

中图分类号：

O4 [物理学];

学科分类号：

0702 ;

摘要：

Using neutron and resonant X-ray scattering, we studied crystal structure and charge-ordering pattern in La1.5Ca0.5CoO4. Taking A2mm with a-b type twin structure into account, Co2+/Co3+ checkerboard charge ordering pattern was suggested in La1.5Ca0.5CoO4 by neutron scattering structure analysis. In order to clarify the charge ordering pattern and the valences of the two Co sites, we performed a resonant X-ray scattering (RXS) measurement near the Co K-edge. We found a resonant signal at (3, 0, 0) reflection which corresponds to the charge ordering with a Co2+/Co3+ checkerboard pattern, and the Co valences of charge ordering were fully charge disproportionated. From the X-ray fluorescence spectra, we found the pre-edge peak structures at E = 7.7 10 and 7.713 keV, corresponding to 1S --> t(2g) and 1s ---> e(g) transitions, respectively. The polarization dependence of the latter one suggests that the anisotropy e(g) orbital is realized in La1.5Ca0.5CoO4.

引用

页数：6

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