Quantum spin liquid: design of a quantum spin liquid next to a superconducting state based on a dimer-type ET Mott insulator
Quantum spin liquid: design of a quantum spin liquid next to a superconducting state based on a dimer-type ET Mott insulator
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DOI：
10.1039/c4tc01701c
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发表时间：
2015-01-01
影响因子：
6.4
通讯作者：
Kishida, Hideo
中科院分区：
文献类型：
--
作者：
Hiramatsu, Takaaki;Yoshida, Yukihiro;Kishida, Hideo
自旋无序量子态的存在是由万尼尔在1950年和安德森在1973年从理论上预测的。在2003年发现第一个量子自旋液体（QSL）系统之前，已经考虑了各种目标材料：莫特绝缘体kappa-(ET)(2)Cu-2(CN)(3)，其中ET是二（乙烯二硫）四硫代烯。二聚体型ET导体kappa-(ET)(2)X（其中X =阴离子）根据反阴离子表现出从绝缘体到金属到超导体的各种传导曲线。在kappa-(ET)(2)X中，阴离子分子形成阴离子开口的特征模式，每个阴离子开口上都有一个对应于单个自旋位点的ET二聚体，即key-keyhole关系。晶体结构的拓扑考虑提供了自旋几何（t′/t）和电子相关（U/W）的信息，其中t和t′是具有等腰三角形几何结构的中间体转移相互作用，U和W分别是现场库仑排斥能和带宽。QSL体系kappa-(ET)(2)Cu-2(CN)(3)在室温下具有一个包含近等边三角形（t′/t = 1.09）的自旋晶格，具有很强的电子相关性（U/W = 0.93）。t′/t和U/W的温度依赖性是理解kappa-(ET)(2)X输运和磁性行为的基础。kappa-(ET)(2)Cu-2(CN)(3)在压力下没有经过反铁磁态，在QSL态旁边具有超导态。本文以kappa-(ET)(2)X的晶体、电子结构和物理性质为基础，利用key-keyhole关系和温度变化带参数t、t′、U和W，讨论了超导态下QSL系统的设计。
The existence of a spin-disordered quantum state was predicted theoretically by Wannier in 1950 and Anderson in 1973. Various target materials had been considered before the discovery of the first quantum spin liquid (QSL) system in 2003: a Mott insulator kappa-(ET)(2)Cu-2(CN)(3), where ET is bis(ethylenedithio) tetrathiafulvalene. The family of dimer-type ET conductors kappa-(ET)(2)X (where X = an anion) exhibits various conduction profiles ranging from insulators to metals to superconductors depending on the counter anion. In kappa-(ET)(2)X, the anion molecules form characteristic patterns of anion openings, on each of which an ET dimer corresponding to a single spin site is positioned, namely a key-keyhole relation. The topological consideration of the crystal structure affords the information on both a spin geometry (t'/t) and electron correlation (U/W), where t and t' are interdimer transfer interactions with an isosceles triangular geometry, and U and W are the on-site Coulomb repulsion energy and bandwidth, respectively. The QSL system kappa-(ET)(2)Cu-2(CN)(3) is characterized by a spin lattice containing nearly equilateral triangles (t'/t = 1.09) with strong electron correlations (U/W = 0.93) at room temperature. The temperature dependences of t'/t and U/W are bases to understand the transport and magnetic behaviors of kappa-(ET)(2)X. kappa-(ET)(2)Cu-2(CN)(3) has a superconducting state next to the QSL state under pressure without passing through an antiferromagnetic state. Here, the design of QSL systems next to a superconducting state is discussed based on the crystal and the electronic structures and physical properties of kappa-(ET)(2)X using the key-keyhole relation and temperature variant band parameters t, t', U, and W.