National Institute for Materials Science (NIMS), International Center for Materials Nanoarchitechtonics (MANA), Namiki 1-1, Tsukuba 305-0044, Japan.
Advanced Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan.
Nat Commun. 2015 Jan 27;6:6091. doi: 10.1038/ncomms7091.
Interplay among various collective electronic states such as charge density wave and superconductivity is of tremendous significance in low-dimensional electron systems. However, the atomistic and physical nature of the electronic structures underlying the interplay of exotic states, which is critical to clarifying its effect on remarkable properties of the electron systems, remains elusive, limiting our understanding of the superconducting mechanism. Here, we show evidence that an ordering of selenium and sulphur atoms surrounding tantalum within star-of-David clusters can boost superconductivity in a layered chalcogenide 1T-TaS2-xSex, which undergoes a superconducting transition in the nearly commensurate charge density wave phase. Advanced electron microscopy investigations reveal that such an ordered superstructure forms only in the x area, where the superconductivity manifests, and is destructible to the occurrence of the Mott metal-insulator transition. The present findings provide a novel dimension in understanding the relationship between lattice and electronic degrees of freedom.
各种集体电子态（如电荷密度波和超导性）之间的相互作用在低维电子系统中具有重要意义。然而，对于奇异态相互作用下的电子结构的原子和物理本质，这对于阐明其对电子系统显著性质的影响至关重要，但仍难以捉摸，限制了我们对超导机制的理解。在这里，我们证明了在星型团簇中硒和硫原子围绕钽的有序排列可以增强层状硫属化物 1T-TaS2-xSex 的超导性，该化合物在近乎完全协调的电荷密度波相中经历超导转变。先进的电子显微镜研究表明，这种有序的超结构仅在超导性表现的 x 区域形成，并且对于莫特金属-绝缘体转变的发生是可破坏的。本研究结果为理解晶格和电子自由度之间的关系提供了一个新的维度。
