FLEET Seminar: Wen-Xin Tang – Surface electron microscopy and its applications on two-dimensional materials

Surface electron microscopy and its applications on two-dimensional materials

Wen-Xin Tang

College of Materials Science and Engineering, Chongqing University,

All welcome! The seminar flyer can be downloaded at this link.

About the Speaker:

Professor Wen-Xin Tang is working in the Material Science and Engi-neering at Chongqing University (CQU), China. He also acts as Deputy Director of Electron Microscopy Center at CQU.

Wen-Xin’s research ex-plores low dimensional materials and surface science by developing novel low energy electron microscopy and spectroscopy. Currently, he is developing unique ultrafast spin polarized LEEM which can be used to explore structural, chemical, spin and charge dynamics in time domain for two-dimensional materials.

Abstract:

The study and control of two dimensional materials are of great interest both from a fundamental point of view and for important applications in the technology of information. This talk will discuss our recent research by using low energy electron microscopy (LEEM) for two-dimensional materials. Fundamental questions of intensity, resolution and contrast will be discussed through examples such as in-plane ferroelectric In₂Se₃ [1], silicon-based 2D monolayer Cu₂Si and self-assembling process of graphene with intercalated alkali metal. The unique contrast mechanism and dynamic process of in-situ LEEM provide direct evidences of dynamic change in between atomic layers of 2D materials.

We further describe the design and commission of a novel aberration-corrected low energy electron microscope and photoemission electron microscopy (ac-LEEM/PEEM) at Chongqing University. A third magnetic prism array (MPA) is implemented to the standard ac-LEEM with two prism arrays, allowing introduce of an ultrafast spin-polarized elec-tron source [2]. The commission of the ac-LEEM has been successfully finished with the cold field emission source, with high spatial resolution at nm. Using such unique platform, a comprehensive (structural, chemical, magnetic, electronic and charge) dynamic characterization on the nm scale in time domain for 2D materials became feasible.

[1] Changxi Zheng, Lei Yu, Lin Zhu, James L Collins, Dohyung Kim, Yaoding Lou, Chao Xu, Meng Li, Zheng Wei, Yupeng Zhang, Mark T Edmonds, Shiqiang Li, Jan Seidel, Ye Zhu, Jefferson Zhe Liu, Wen-Xin Tang, Michael S Fuhrer, Science Advances, 4 (7), eaar7720, 2018
[2] Weishi Wan, Lei Yu, Lin Zhu, Xiaodong Yang, Zheng Wei, Jefferson Zhe Liu, Jun Feng, Kai Kunze, Oliver Schaff, Ruud Tromp, Wen-Xin Tang, Ultramicroscopy, 174, 89, 2017