题目：Quantum Materials Based on Epitaxial Moirè Superlattices

报告人：王学森 副教授（新加坡国立大学）

地点：紫金港西区海纳苑8幢215报告厅

时间：2023年4月10日（周一），下午16：00 

摘要：In recent years, the moirè superlattices formed with twisted homo- or hetero-bilayer of graphene or TMDCs have been investigated intensively.  Such moiré bilayers provide us with a class of designed nanomaterials that possess novel electronic properties, including flat energy bands and heavy fermions.  These moiré structures can exhibit metal-insulator transition, superconductivity and topological insulators.  The moiré structures constructed from the exfoliated atomic layers, however, have certain limitations that severely hinder their further development and applications in nano-electronics and photonics.  To expand the family of such electronic systems, we are investigating the moirè superlattices formed with atomic overlayers epitaxially grown on suitable crystalline substrates. To realize the epitaxial moirè structures, the atomic layer and the substrate should have a lateral period mismatch of about 5-10%; the interfacial binding strength should be in the van der Waals range; then the electronic states of the overlayer are perturbed with a moderate moiré periodic potential. Such epitaxial moiré systems offer certain advantages over those twisted bilayers made of exfoliated layers in terms of accessible material and electronic parameter ranges, sample quality and practical device mass production.  Possible candidates of such epitaxial moiré system we have explored include Group-VA (P, As, Sb and Bi) atomic layers on Group IV-VI or other bulk crystals. The exploration can be extended to a much broad range of overlayers and substrates. The possibility of tuning the interfacial coupling strength will be demonstrated and discussed.  

个人简介：

王学森，新加坡国立大学物理系副教授。1982 年在中国复旦大学取得物理学学士学位，1990年在美国马里兰大学取得物理学博士学位，先后在美国加州圣塔芭芭拉分校，美国明尼苏达大学，美国马里兰大学，香港科技大学从事研究和教学工作。2001年起加入新加坡国立大学物理系工作至今。主要利用扫描隧道显微镜和光谱(STM和STS)来表征表面、薄膜和纳米结构的特征。目前研究方向为（1） 石墨、硫化钼和硅基底上自组装和自组织纳米结构：金（Au）、铂（Pt）、钯（Pd）、二氧化钛（Ti）、氮化钛（TiN）、锰（Mn），锑化锰（MnSb））的生长和扫描隧道显微镜表征；（2）金属半导体混合纳米结构: 形态和原子结构控制，表面等离子共振, 有机分子与半导体或金属纳米结构之间形成的混合系统混合结构在分子电子学和催化中应用研究；(3)二维材料与外延生长摩尔超晶格。

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