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arXiv 0904.4338cond-mat.str-elcond-mat.mtrl-sci
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碱金属倍半氧化物Rb4O6和Cs4O6的奇异磁性

Exotic magnetism in the alkali sesquoxides Rb4O6 and Cs4O6

Juergen Winterlik, Gerhard H. Fecher, Taras Palasyuk, Claudia Felser, Juergen Kuebler, Claus Muehle, Martin Jansen, Ivan Trojan, Sergey Medvedev, Mikhail I. Ere… 展开作者

Juergen Winterlik, Gerhard H. Fecher, Taras Palasyuk, Claudia Felser, Juergen Kuebler, Claus Muehle, Martin Jansen, Ivan Trojan, Sergey Medvedev, Mikhail I. Eremets, Franziska Emmerling

摘要:

在各种碱金属氧化物中,特别感兴趣的是倍半氧化物Rb_4O_6和Cs_4O_6。电子结构计算使用本地自旋密度近似预测,Rb 4 O 6应该是一个半金属铁磁体,这是后来矛盾时,实验研究的温度依赖的磁化强度的Rb 4 O 6显示低温磁转变和零场冷却(ZFC)和场冷却(FC)测量之间的差异。这种行为从自旋玻璃和受抑系统中已知。Rb 4 O 6和Cs4 O 6包含两种不同类型的二氧阴离子,超氧阴离子和过氧化物阴离子。过氧化氢阴离子不含未成对电子,而过氧化氢阴离子在反键π *-轨道中含有未成对电子。高电子局域化(窄带)表明,电子相关性是非常重要的,在这些开壳层p-电子系统。相关性和电荷排序,由于混合价呈现p-电子为基础的阴离子磁序可能在倍半氧化物。在这项工作中,我们提出了一个实验比较的Rb_4O_6和相关的Cs_4O_6。使用粉末X射线衍射验证晶体结构。这两种化合物的混合价确认使用拉曼光谱,和随时间变化的磁化实验表明,这两种化合物显示磁挫折,以前只知道从d-和f-电子系统的功能。

英文摘要:

Among the various alkali oxides the sesquioxides Rb4O6 and Cs4O6 are of special interest. Electronic structure calculations using the local spin-density approximation predicted that Rb4O6 should be a half-metallic ferromagnet, which was later contradicted when an experimental investigation of the temperature dependent magnetization of Rb4O6 showed a low-temperature magnetic transition and differences between zero-field-cooled (ZFC) and field-cooled (FC) measurements. Such behavior is known from spin glasses and frustrated systems. Rb4O6 and Cs4O6 comprise two different types of dioxygen anions, the hyperoxide and the peroxide anions. The nonmagnetic peroxide anions do not contain unpaired electrons while the hyperoxide anions contain unpaired electrons in antibonding pi*-orbitals. High electron localization (narrow bands) suggests that electronic correlations are of major importance in these open shell p-electron systems. Correlations and charge ordering due to the mixed valency render p-electron-based anionogenic magnetic order possible in the sesquioxides. In this work we present an experimental comparison of Rb4O6 and the related Cs4O6. The crystal structures are verified using powder x-ray diffraction. The mixed valency of both compounds is confirmed using Raman spectroscopy, and time-dependent magnetization experiments indicate that both compounds show magnetic frustration, a feature only previously known from d- and f-electron systems.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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