Electronic phase transition between localized and itinerant states in the solid-solution system CaCu3Ti(4-x)RuxO12
Electronic phase transition between localized and itinerant states in the solid-solution system CaCu3Ti(4-x)RuxO12
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固溶体体系 CaCu3Ti(4-x)RuxO12 中局域态和巡回态之间的电子相变
DOI：
10.1103/physrevb.95.195141
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发表时间：
2017
影响因子：
3.7
通讯作者：
and Hung-Duen Yang
中科院分区：
文献类型：
--
作者：
Ting-Hui Kao Hiroya Sakurai;Shan Yu;Harukazu Kato; Naohito Tsujii; and Hung-Duen Yang
采用高压技术首次合成了端部之间的固溶体。在2 K处的剩余磁化强度急剧变化，在1 K处的自旋玻璃样相突然消失，提示发生了一阶电子相变。磁化率对温度有较强的依赖性，对温度有较弱的依赖性。在中间值时，高温下的弱依赖性变为低温下的强依赖性。在8.5 K和3.5 K时，电阻率为变量程跳变型，而在2.5 K和3.0 K时，电阻率由后者变为前者。基于这些结果的电子相图类似于显示莫特跃迁的有机系统的电子相图，也类似于莫特跃迁的理论图。结合电子能带结构计算，随着Ru含量的增加，Ti化合物方区局部磁矩通过一阶相变变得流动，表明这种转变可以看作是Mott转变。Mott跃迁的独特之处在于Ru态的原子轨道对类分子轨道的电子/空穴跳变幅度的增加起着重要的作用。
A solid solution betweenend members was first synthesized using a high-pressure technique. The residual magnetization at 2 K sharply changes at, and a spin-glass-like phase suddenly disappears at, suggesting a first-order electronic phase transition. The magnetic susceptibility shows a strong dependence on the temperature forand a weak dependence for. At an intermediate value of, the weak dependence at high temperatures changes to a strong dependence at low temperatures. The electrical resistivity shows variable-range-hopping-type behavior forand metallic behavior for, changing from the latter to the former at, 8.5, and 3.5 K for, 2.5, and 3.0, respectively. An electronic phase diagram based on these results is similar to that for an organic system showing a Mott transition and to a theoretical diagram for the Mott transition. Considering electronic band structure calculations, the local magnetic moments at thesquares of the Ti compound become itinerant with increasing Ru content by means of a first-order phase transition, suggesting that the transition can be regarded as a Mott transition. The Mott transition is unique in that the atomic orbitals of the Ru cations play an important role in the increased hopping amplitude of the electrons/holes of themolecularlike orbitals.