Department of Physics, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan.
Department of Physics, Graduate School of Science, University of Tokyo, Tokyo 113-0033, Japan.
Science. 2017 Nov 24;358(6366):1084-1087. doi: 10.1126/science.aah4297.
Mott insulators can host a surprisingly diverse set of quantum phenomena when their frozen electrons are perturbed by various stimuli. Superconductivity, metal-insulator transition, and colossal magnetoresistance induced by element substitution, pressure, and magnetic field are prominent examples. Here we report strong diamagnetism in the Mott insulator calcium ruthenate (CaRuO) induced by dc electric current. The application of a current density of merely 1 ampere per centimeter squared induces diamagnetism stronger than that in other nonsuperconducting materials. This change is coincident with changes in the transport properties as the system becomes semimetallic. These findings suggest that dc current may be a means to control the properties of materials in the vicinity of a Mott insulating transition.
当莫特绝缘体的冻结电子受到各种刺激时,它们可以承载一系列令人惊讶的量子现象。由元素替代、压力和磁场引起的超导性、金属-绝缘体转变以及巨大磁电阻是突出的例子。在这里,我们报告了由直流电流引起的莫特绝缘体钙钌酸盐 (CaRuO) 的强抗磁性。仅仅每平方厘米 1 安培的电流密度就能产生比其他非超导材料更强的抗磁性。这种变化与系统变为半金属时输运性质的变化一致。这些发现表明,直流电流可能是控制莫特绝缘转变附近材料性质的一种手段。