报告题目：Flat electronic bands in transition metal dichalcogenides

报告人：季威教授    中国人民大学物理学院

报告时间：2024年03月26日（周二）14:30

报告地点：理六栋525        

邀请人：赵纪军

报告内容：

Flat electronic bands near the Fermi level provide a fertile playground for realizing  interaction-driven correlated physics. To date, related experiments have mostly been limited to engineered multilayer systems (e.g., moiré systems). Herein, we report theoretical predictions and experimental realizations of nearly flat bands near or even across the Fermi level in monolayer MoTe2-x by fabricating a series of uniformly ordered mirror-twin boundary superlattices (corresponding to a stoichiometry of MoTe8/5 and MoTe56/33). Kagome flat bands were predicted by density functional theory calculations and were discovered by scanning tunnelling microscopy. For the monolayer where a flat electronic band residing across the Fermi level, the partial filling nature of flat bands yields a correlated insulating state exhibiting a hard gap as large as 15 meV. Moreover, we observe pronounced responses of the correlated states to magnetic fields, providing evidence for a spin-polarized ground state. In addition, we also observed a similar geometric symmetry and flat electronic bands in another transition metal dichalcogenide material through lattice distortion induced by charge density wave. Our work introduces monolayer platforms that manifests strong correlation effects arising from flattened electronic bands.

专家简介：

季威，中国人民大学吴玉章讲席教授，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200余篇，被引约14000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才奖励计划特聘教授，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。