Quantum paramagnet near spin-state transition
Quantum paramagnet near spin-state transition
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近自旋态跃迁的量子顺磁体
DOI：
10.1002/qute.201800057
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发表时间：
2018
期刊：
影响因子：
--
通讯作者：
M. Kofu and S. Ishihara
中科院分区：
文献类型：
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作者：
K. Tomiyasu;N. Ito;R. Okazaki;Y. Takahashi;M. Onodera;K. Iwasa;T. Nojima;T. Aoyama;K. Ohgushi;Y. Ishikawa;T. Kamiyama;S. Ohira-Kawamura;M. Kofu and S. Ishihara
自旋态转变，也称为自旋交叉，在包括矿物和生物材料在内的各种系统中起着关键作用。理论上，低自旋态和高自旋态之间的边界范围预计会丰富跃迁并产生不寻常的物理状态。然而，没有化合物，实现了近简并的临界范围作为基态，而不需要特殊的外部条件尚未被实验确定。本研究通过宏观物理性质、X射线衍射和中子能谱的综合测量，发现Sc取代LaCoO3使其低自旋态不稳定，产生了反常顺磁态，并伴随着输运能隙的增强和磁晶格膨胀，以及随着电子位转移的增加，Co─O距离的收缩。这些现象不能用传统的低自旋和高自旋态的混合来很好地描述，而是在自旋态跃迁的边缘发生的量子叠加。目前的研究使我们能够显着加快新的先进材料的设计，而不需要特殊的设备，基于量子自旋态临界性的概念。
Spin‐state transition, also known as spin crossover, plays a key role in diverse systems, including minerals and biological materials. In theory, the boundary range between the low‐ and high‐spin states is expected to enrich the transition and give rise to unusual physical states. However, no compound that realizes a nearly degenerate critical range as the ground state without requiring special external conditions has yet been experimentally identified. This study reports that, by comprehensive measurements of macroscopic physical properties, X‐ray diffractometry, and neutron spectroscopy, the Sc substitution in LaCoO3destabilizes its nonmagnetic low‐spin state and generates an anomalous paramagnetic state accompanied by the enhancement of transport gap and magneto‐lattice‐expansion as well as the contraction of Co─O distance with the increase of electron site transfer. These phenomena are not well described by the mixture of conventional low‐ and high‐spin states, but by their quantum superposition occurring on the verge of a spin‐state transition. The present study enables us to significantly accelerate the design of new advanced materials without requiring special equipment, based on the concept of quantum spin‐state criticality.