报告题目：Exotic electronic states in low-dimensional super-atomic crystals

报告人：季威 教授（中国人民大学）

报告时间：2023年4月20日（星期四）, 上午10：00

地点： 致知楼3624

摘要：

Electronic properties of super-atomic crystals have not been sufficiently explored due to the versatility of their building units; moreover, their interunit couplings are even poorly understood. In this talk, I will show exotic electronic states hosted in two super-atomic crystals, one exists in nature and the other was purely artificial, as observed in scanning tunneling microscopic images/spectra and verified/predicted by density functional theory calculations. One example lies in a layered super-atomic crystal of Au₆Te₁₂Se₈ (ATS) cubes stacked by noncovalent inter-cube quasi-bonds. We find a sequential-emerged anisotropic triple-cube charge density wave (TCCDW) and polarized metallic states below 120 K. The polarized states are locked in an antiparallel configuration, which is required for maintaining the inversion symmetry of the center cube in the TCCDW. The antipolar metallic states are thus interweaved by the CDW and the polarized metallic states, and primarily ascribed to electronic effects via theoretical calculations. The other example was illustrated using MoTe2 monolayers. A coloring-triangle (CT) latticed MoTe₂ monolayer (see below), termed CT-MoTe₂, was constructed by controllably introducing uniform and ordered mirror-twin-boundaries into a pristine monolayer in molecular beam epitaxy. This monolayer has an electronic Janus lattice, i.e., an energy-dependent atomic-lattice and a pseudo-Te sublattice, and shares the identical geometry with the Mo₅Te₈ layer. 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.

   报告人简介：

    季威，中国人民大学杰出学者特聘教授。2010年进入中国人民大学物理学系工作任副教授，2014年晋升教授。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、二维材料、新型低维超原子材料和信息功能材料与器件的表界面问题。发表论文190余篇，被引超过1.2万次 (Web of Science)，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。曾获北京市科学技术二等奖、中国发明协会发明创业奖创新二等奖和成果二等奖。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。