National Laboratory of Solid State Microstructures, School of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University , Nanjing 210093, China.
School of Material Science and Engineering, Southwest University of Science and Technology , Mianyang 621010, China.
Nano Lett. 2018 Feb 14;18(2):1410-1415. doi: 10.1021/acs.nanolett.7b05157. Epub 2018 Feb 5.
Layered metal chalcogenide materials provide a versatile platform to investigate emergent phenomena and two-dimensional (2D) superconductivity at/near the atomically thin limit. In particular, gate-induced interfacial superconductivity realized by the use of an electric-double-layer transistor (EDLT) has greatly extended the capability to electrically induce superconductivity in oxides, nitrides, and transition metal chalcogenides and enable one to explore new physics, such as the Ising pairing mechanism. Exploiting gate-induced superconductivity in various materials can provide us with additional platforms to understand emergent interfacial superconductivity. Here, we report the discovery of gate-induced 2D superconductivity in layered 1T-SnSe, a typical member of the main-group metal dichalcogenide (MDC) family, using an EDLT gating geometry. A superconducting transition temperature T ≈ 3.9 K was demonstrated at the EDL interface. The 2D nature of the superconductivity therein was further confirmed based on (1) a 2D Tinkham description of the angle-dependent upper critical field B, (2) the existence of a quantum creep state as well as a large ratio of the coherence length to the thickness of superconductivity. Interestingly, the in-plane B approaching zero temperature was found to be 2-3 times higher than the Pauli limit, which might be related to an electric field-modulated spin-orbit interaction. Such results provide a new perspective to expand the material matrix available for gate-induced 2D superconductivity and the fundamental understanding of interfacial superconductivity.
层状金属硫属化物材料为研究新兴现象和二维（2D）超导提供了一个通用平台，在原子级薄的极限附近。特别是，通过使用双电层晶体管（EDLT）实现的栅极诱导界面超导，极大地扩展了在氧化物、氮化物和过渡金属硫属化物中电诱导超导的能力，并使人们能够探索新的物理现象，如 Ising 配对机制。利用各种材料中的栅极诱导超导可以为我们提供更多的平台来理解新兴的界面超导。在这里，我们报告了在主族金属二硫属化物（MDC）家族的典型成员 1T-SnSe 中发现的通过 EDLT 栅极几何结构诱导的二维超导。在 EDL 界面上证明了超导转变温度 T ≈ 3.9 K。超导的二维性质进一步通过以下几点得到证实：(1) 对角度相关的上临界场 B 的二维 Tinkham 描述；(2) 量子蠕变状态以及超导相干长度与厚度之比的存在。有趣的是，发现平行于平面的 B 接近零温度时比 Pauli 极限高 2-3 倍，这可能与电场调制的自旋轨道相互作用有关。这些结果为扩展可用于栅极诱导 2D 超导的材料矩阵以及界面超导的基本理解提供了新的视角。
