报告人：季威教授，中国人民大学

邀请人：王健教授

时 间：2023年9月1日上午10:00

地 点：致原楼1101会议室

报告摘要：

In this talk, I will be presenting a “surface” kagome electronic state found on the Sn terminated surface of Co₃Sn₂S₂, although Sn (and S) atoms of the surface are arranged in a triangular (hexagonal) lattice [1]. This finding enlightens the routes for building kagome electronic state down to the two-dimensional limit. Next, I will be showing kagome electronic bands, namely a set of one topological flat band and two Dirac bands, inpost-annealed MoTe₂monolayers. A coloring-triangle (CT) latticed MoTe₂monolayer [2], termed CT-MoTe₂, was constructed by controllably introducing uniform and ordered mirror-twin-boundaries into a pristine monolayer. This CT-MoTe₂monolayer has an electronic Janus lattice, i.e., an energy-dependent atomic-lattice and a pseudo-Te sublattice, and shares the identical geometry with the Mo₅Te₈layer. Dirac-like and flat electronic bands inherently existing in the CT lattice are identified by two broad and two prominent peaks in STS spectra, respectively, and verified with DFT calculations. Further explore this category of post-annealed MoTe₂monolayers, we found another defective monolayer [3], namely Mo₃₃Te₅₆, which is the most stable monolayer in a certain range of the chemical potential of Te. This monolayer contains two sets of kagome bands across the Fermi level, while the nominal flat band of one of the two sets shows a corelated gap with inequivalent responses to external magnetic fields. If I still have time, I willbecommenting on the validity of multiferroicity in the NiI₂monolayer, a type-II multiferroic monolayer in debate [4].

References:

[1] L. Huang,et. al.arXiv:2305.00826 (2023), Nature Communications, in press.

[2] L. Lei,et. al.arXiv:2302.06166 (2023).

[3] Z. Pan,et. al.arXiv:2307.06001(2023).

[4] N. Liu,et al.arXiv: 2211.14423v3 (2023)

报告人简介：

季威教授，中国人民大学“杰出学者”特聘教授，国家高层次人才奖励计划特聘教授。研究兴趣主要为发展和应用独特的第一性原理计算方法，与实验紧密结合，模拟和预测低维量子系统和信息材料与器件的界面前沿问题。发表论文近200篇，被引约13000次（WoS数据），部分研究成果被选为2011年国际邮票素材、入选2013中国科学十大进展、2014年和2015年中国百篇最具影响国际学术论文。2014-2016年获得三个国家级青年人才计划或创新项目支持，2019年入选中科院青促会首批特邀会员，2021年入选国家高层次人次奖励计划特聘教授，2023年被选为四川省天府学者。目前担任中国材料研究学会计算材料学委员会委员；ACS Applied Electronic Materials副主编，Science Bulletin、Chinese Physics B、《物理学报》、2D Materials和Frontiers of Physics编委等。

欢迎各位老师和同学参加!