RIKEN, Hirosawa, Wako, Saitama 351-0198, Japan.
Research Center for Integrative Molecular System (CIMoS), Institute for Molecular Science , 38 Nishigo-naka, Myodaiji, Okazaki 444-8585, Japan.
Nano Lett. 2017 Feb 8;17(2):708-714. doi: 10.1021/acs.nanolett.6b03817. Epub 2017 Jan 10.
We present the carrier transport properties in the vicinity of a doping-driven Mott transition observed at a field-effect transistor (FET) channel using a single crystal of the typical two-dimensional organic Mott insulator κ-(BEDT-TTF)CuN(CN)Cl (κ-Cl). The FET shows a continuous metal-insulator transition (MIT) as electrostatic doping proceeds. The phase transition appears to involve two-step crossovers, one in Hall measurement and the other in conductivity measurement. The crossover in conductivity occurs around the conductance quantum e/h, and hence is not associated with "bad metal" behavior, which is in stark contrast to the MIT in half-filled organic Mott insulators or that in doped inorganic Mott insulators. Through in-depth scaling analysis of the conductivity, it is found that the above carrier transport properties in the vicinity of the MIT can be described by a high-temperature Mott quantum critical crossover, which is theoretically argued to be a ubiquitous feature of various types of Mott transitions.
我们展示了在典型二维有机莫特绝缘体 κ-(BEDT-TTF)CuN(CN)Cl（κ-Cl）单晶的场效应晶体管（FET）沟道中，在掺杂驱动的莫特转变附近的载流子输运性质。随着静电掺杂的进行，FET 显示出连续的金属-绝缘体转变（MIT）。相变似乎涉及两个步骤的交叉，一个在 Hall 测量中，另一个在电导率测量中。电导率的交叉发生在电导量子 e/h 附近，因此与“坏金属”行为无关，这与半满有机莫特绝缘体或掺杂无机莫特绝缘体中的 MIT 形成鲜明对比。通过对电导率的深入标度分析，发现 MIT 附近的上述载流子输运性质可以用高温莫特量子临界点交叉来描述，这在理论上被认为是各种类型的莫特转变的普遍特征。
