高压下过渡金属二硫属化物的超导电性

Pressure-tunable superconductivity in transition-metal dichalcogenides

过渡金属二硫属化物是一类典型的二维类石墨烯层状结构的材料,相比于石墨烯的全碳元素组成以及无带隙的电子结构特点,具有更丰富的元素组成、多样的微观结构和奇异的物理性质。过渡金属二硫属化物强烈的各向异性以及在催化、光伏器件和储能材料等领域的优异表现,引起了科学家们浓厚的研究兴趣。它们的层间范德瓦耳斯间隙、层间范德瓦耳斯相互作用、层间堆垛次序对压力非常敏感,易于通过压力调控其晶体结构和电子能带结构,进而发生电子基态的变化。过渡金属二硫属化物的电子基态可以是莫特绝缘体、激子绝缘体、电荷密度波、半导体、(拓扑)半金属、金属,甚至是超导体。在常压条件下,部分过渡金属二硫属化物具有超导电性。实验表明,压力可以诱导过渡金属二硫属化物非超导母体发生超导转变,或者提高超导母体的超导转变温度。文章以典型的过渡金属二硫属化物为例,概述了其在高压调控下超导电性的响应,并简要讨论产生超导电性的物理机制。

Transition metal dichalcogenides(TMDs)are typical two-dimensional graphenelike layered structure materials.Compared with graphene’s all-carbon composition and bandgapfree electronic structure,TMDs have more abundant element composition,various crystal structure and novel physical properties.Their strong anisotropy and excellent performance in catalysis,photovoltaic devices and energy storage materials have aroused great interest of scientists.These layered structure TMDs are very sensitive to pressure due to their interlayer stacking mode and weak interlayer van der Waals forces,and it is easy to alter their crystal structure and electronic band under high pressure,and further to change the electronic ground state.they span a wealth of electronic ground states encompassing Mott insulators,excitonic insulators,charge density waves,semiconductors,(topological)semimetals,metals,and superconductors.Some pristine polymorphs can even exhibit intrinsic superconductivity at ambient pressure.Experiments show that extrinsic superconductivity can be induced or enhanced in a multitude of pristine polymorph TMDs via external pressure.In this review,the emergence and evolution of superconductivity in these polymorphs upon application of pressure is addressed.