Upon the invitation of the School of Physical Science and Technology and the Cuiying Honors College, researcher Xu Hai from the Institute of Optics, Fine Mechanics and Physics of the Chinese Academy of Sciences will attend the 35th series of Enlightenment Forum. Attendance is welcome.
Title: Surface-Limited Superconducting Phase Transition on TMDS
Time: 14:30 p.m., November 27, 2018, 14:30
Location: Conference Room 3016, Gezhi Building
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 tunneling 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 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)
About Dr. Xu Hai
Dr. Xu Hai is now a research fellow at the State Key Laboratory of Luminescence and Applications of Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences. He graduated from the Physics Department of Lanzhou University and worked on the growth of low-dimensional materials and surface physics at the Max-Planck Institute of Microstructure Physics, the National University of Singapore, and the Center for Materials and Structures Research of the French Academy of Sciences (Toulouse). Later, he joined the US company Zyvex Nanotechnology Co., Ltd. in the research and development of Atomic Precise Manufacturing. In 2016, he returned to China and joined the Changchun Institute of Optics and Mechanics of the Chinese Academy of Sciences. He was an award winner of the “Hundred Talents Program” of the academy and gained the title of “high-level innovative and entrepreneurial talent” of Jilin Province.
Dr. Xu’s current research interests include surface physics, new low-dimensional semiconductor optoelectronic materials, and device characteristics, and advanced micro-nano scanning in probe detection and processing. He has published more than 70 high-level SCI articles on Nature Nanotechnology, Nature Communications, Physical Review Letters, J.Am.Chem.Soc., Advanced Materials and Advanced Functional Materials. He also owns two proprietary inventions.
