【学术视频】第二十二届全国半导体物理学术会议 | 中国人民大学季威教授

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图 | 季威

题   目：Interlayer magnetic coupling mechanism in CrI₃ and CrX₂报告人：季威单   位：中国人民大学时   间：2019-07-11地   点：中国杭州

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报告摘要

Van der Waals forces were believed dominant for interlayer interactions in layered two-dimensional (2D) materials. We recently found an emergent type of interlayer interactions, namely covalent-like quasi-bonding (CLQB), in various 2D materials like black phosphorus, PtS₂, PtSe₂ and few-layer Te. This interlayer interaction is, most likely, directly observed in TiS₂ by x-ray scattering. Such technique also suggested charge accumulation in hydrogen bonds. We thus imaged intermolecular hydrogen bonds in real space using a qPlus non-contact Atomic Force Microscope with a CO terminated tip, which suggests a covalent characteristic of hydrogen bonds. However, it was argued that the contrast between molecules is a result of CO tip tilting, which boost extensive discussions in the field. In collaboration with our experimental and theoretical coworkers, we found an O atom modified Cu tip is of strong lateral stability which is an order of magnitude higher than the usual CO modified tip. It does not show the fake contract between two S atoms in the adsorbed DBTH molecule on Cu (110), but does show the N...N bond in BPPA and hydrogen bonds in PTCDA. In addition, we discussed the interlayer magnetic couplings (IMC) of CrS₂ and CrI₃ bilayers. It is interesting that these two materials are at two extremes of IMC. The interlayer FM coupling in CrS₂ is very robust and is nearly unable to be tuned under usual external fields, but the intra-layer magnetism does be varied under layer stacking. An opposite case was found in CrI₃ bilayers where the intra-layer FM coupling is, however, very strong but the interlayer magnetism was found governed by a subtle change of interlayer stacking; this shows a decoupled magnetic interaction between intra- and inter-layer directions.

个人简介

季威，中国人民大学青年学者、教授。长期致力于发展和应用独特的第一性原理计算方法，研究了多种表面量子系统和信息材料与器件等领域的前沿问题；发展了新方法，预测了新现象并部分被实验证实，解释了实验现象并提出相应的新机理和新理论，取得了一系列有国际影响力的成果。发表了包括Science, Science Advances, Nature Communications, Nature Chemistry, Nature Nanotechnology, PRL, JACS, Nano Letters, ACS NANO, Advanced Materials等近40篇高端论文在内的80余篇论文，总被引超过2800次，ESI高被引论文9篇，热点论文2篇，H因子25。2011年入选教育部新世纪优秀人才支持计划、当选中国材料研究学会青委会理事；2015年入选中组部青年拔尖人才、入选教育部奖励计划青年学者；2016年获得优秀青年科学基金支持。其研究兴趣: 1、新兴低维信息和能源材料与器件物理：二维信息、光电材料物性预测、低维小量子体系输运性质预测、低维光电转换材料设计、透射电子显微镜电子激发态模拟；2、表面和界面上的物理、化学过程：功能化原子力显微镜模拟、表面小量子体系中的特殊电子态预测、电子激发态下的物理化学过程模拟。

会议简介

第二十二届全国半导体物理学术会议是浙江大学物理学系和浙江大学硅材料国家重点实验室承办，由中国物理学会半导体物理专业委员会主办的全国性会议。会议宗旨是促进国内半导体物理研究领域的学术交流，把握国际重大前沿领域的发展动向，提升国内半导体物理及相关学科的国际影响力。本届会议于2019年7月9~12日在杭州第一世界大酒店召开。朱邦芬院士、黄如院士、杜瑞瑞教授、段镶锋教授、熊启华教授、彭笑刚教授、陆卫教授、陆朝阳教授等知名学者莅临本届会议并作大会特邀报告。

—— ——往期精彩回顾—— ——●【学术视频】凝聚态物理南方论坛 2019 | 季威：非共价相互作用与物性调控●【学术视频】第二十二届全国半导体物理学术会议 | 浙江大学彭笑刚教授：Colloidal Quantum Dots: Synthetic Control and Applications of Excited States●【学术视频】ICFSI-17 | Thierry ANGOT of Aix-Marseille University：Epitaxial graphene and silicene●【学术视频】Topological Physics in Quamtum Materials| Congjun Wu(UCSD)：Quaternionic Analyticity and High Dimensional Topological States●【学术视频】第一届南京量子材料国际会议 | Steven A. Kivelson of Stanford University：Breakdown of Migdal-Eliashberg theory and a bound on Tc.●【学术视频】中国化学会第四届中国能源材料化学研讨会 | 大连理工大学黄瑞研究员：红外光谱揭示二氧化碳转化合成环状碳酸酯●【学术视频】2019中国光电信息功能材料与器件学术高峰论坛 | 南京理工大学曾海波教授：钙钛矿量子点发光显示若干关键问题●【学术视频】2019年复旦大学量子信息与计算暑期学校 | 加州大学圣芭芭拉分校徐一鸿教授：My Adventure in Writing Popular Books and Textbooks

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