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题目：表面调控二维材料的超导相变

Surface-Limited Superconducting Phase Transition on TMDS

时间：2018年11月27日14:30

地点：格致楼3016

Abstract

Controlling superconducting phase transition on two-dimensional (2D) material is of great fundamental and technological interest from the viewpoint of making 2D resistance-free electronic circuits. Here, we demonstrate that a 1T-to-2H phase transition can be induced on the topmost monolayer of bulk (< 100 nm thick) 1T-TaS2 by thermal annealing. The monolayer 2H-TaS2 on bulk 1T-TaS2 exhibits a superconducting transition temperature (Tc) of 2.1 K, which is significantly enhanced compared to that of bulk 2H-TaS2. Scanning tunnelling microscopy measurements reveal a 3×3 charge density wave (CDW) in the phase-switched monolayer at 4.5 K. The enhanced Tc is explained by the suppressed 3×3 CDW and a charge-transfer doping from the 1T substrate. We further show that the monolayer 2H-TaS2 could be switched back to 1T phase by applying a voltage pulse. The observed surface-limited superconducting phase transition offers a convenient way to prepare robust 2D superconductivity on bulk 1T-TaS2 crystal, thereby bypassing the need to exfoliate monolayer samples.

References:

1. Pan, J., Guo, C., Song, C., Lai, X., Li, H., Zhao, W., Zhang, H., Mu, G. et al.Journal of the American Chemical Society 139, 4623(2017)

2. Ma, L., Ye, C., Yu, Y., Lu, X. F., Niu, X., Kim, S., Feng, D., Tománek, D. et al.Nature Communications 7, 10956(2016).

3. Hai Xu,Dong Han,Yang Bao,Fang Cheng,Zijing Ding,Sherman J. R. Tan,Kian Ping Loh; Nano Lett 18, 5085(2018)

4. Xu H, Liu S, Ding Z, Tan S J R, Yam K M, Bao Y, Nai C T, Ng M-F, Lu J, Zhang C and Loh K P; Nature Communications 7,12904 (2016)

徐海个人简介

中国科学院长春光学精密机械与物理研究所，发光学及应用国家重点实验室研究员。徐海博士毕业于兰州大学物理系，先后在德国马克斯.普朗克（Max-Planck）微结构物理研究所，新加坡国立大学，以及法国科学院材料与结构研究中心(Toulouse)从事低维材料生长和表面物理研究工作。后加入美国Zyvex纳米技术公司从事原子级精准制造技术 (Atomic Precise Manufacturing)的研发工作。2016年回国加入中科院长春光机所，入选中科院率先行动“百人计划”技术英才、吉林省“高层次创新创业人才”。

目前研究兴趣包括表面物理，新型低维半导体光电材料与器件特性研究，以及微纳尺度先进扫描探针检测加工技术。已发表包括《Nature Nanotechnology》《Nature Communications》《Physical Review Letters.》《J. Am. Chem.Soc.》《Advanced Materials》《AdvancedFunctionalMaterials》等高水准SCI文章70余篇，拥有发明专利2项。