Unusual Ferromagnetic Metal: A-Site-Layer-Ordered Double Perovskite YBaCo2O6 with Unusually High Valence Co3.5+
Unusual Ferromagnetic Metal: A-Site-Layer-Ordered Double Perovskite YBaCo2O6 with Unusually High Valence Co3.5+
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DOI：
10.1021/acs.chemmater.8b04203
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发表时间：
2018-12-11
影响因子：
8.6
通讯作者：
Shimakawa, Yuichi
中科院分区：
文献类型：
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作者：
Goto, Masato;Saito, Takashi;Shimakawa, Yuichi
A位层有序双钙钛矿结构的YBaCo_2 O_6具有异常高价态的Co_（3.5+），是一种具有强电子关联的铁磁金属。该化合物是通过在低温下在臭氧中局部化学氧化A位层有序的YBaCo 2 O 5而获得的，该化合物含有名义上的Co2.5+。YBaCo_2O_6在室温下为完全氧化的A位层有序的双钙钛矿结构，在140 K以下出现正交畸变。这种各向异性的结构畸变诱导铁磁有序的混合价Co自旋与中间自旋状态，表明在这个系统中的强自旋-晶格耦合。在铁磁态下，主要由杂化Co 3d和0 2 p组成的上自旋带穿过费米能级，表现出金属性质，与强电子关联无关。
A-site-layer-ordered double perovskite YBaCo2O6 with unusually high valence Co3.5+ was found to be an unusual ferromagnetic metal with strong electron correlation. The compound was obtained by topochemically oxidizing the A-site-layer-ordered YBaCo2O5, which contains nominal Co2.5+, in ozone at a low temperature. YBaCo2O6 crystallizes as a fully oxygenated A-site-layer-ordered double perovskite with a tetragonal structure at room temperature and shows an orthorhombic distortion below approximately 140 K. This anisotropic structural distortion induces ferromagnetic ordering of the mixed-valence Co spins with intermediate spin states, suggesting strong spin-lattice coupling in this system. In the ferromagnetic state, the up-spin band mainly consisting of hybridized Co 3d and 0 2p crosses the Fermi level, giving the metallic behavior, regardless of the strong electron correlation.