报 告人：俞弘毅教授（中山大学）

邀 请人：李朝红教授

时　 间：2023年3月10日16:00-17:30

线下地址：沧海校区致原楼1212会议室

会议链接：https://meeting.tencent.com/dm/cQMGmrBPThzD

会议号：腾讯会议：923-176-203

报告摘要：

In binary compound 2D insulators/semiconductors such as hexagonal boron nitride and transition metal dichalcogenides, the different electron affinities of atoms can give rise to out-of-plane electric polarizations across inversion asymmetric van der Waals interface of near 0° twist angles. Here we show that at a general stacking order where sliding breaks the in-plane C3 rotational symmetry, the interfacial charge redistribution also leads to an in-plane electric polarization, with a comparable magnitude to that of the out-of-plane ones. The effect is demonstrated using a hexagonal boron nitride bilayer of the R-type stacking. In long wavelength moiré patterns, the in-plane electric polarizations determined by the local interlayer stacking registries constitute topologically nontrivial spatial textures. We show that these textures can distinguish moiré patterns of different origins from twisting, biaxial- and uniaxial-heterostrain, where vector fields of the electric polarizations feature Bloch type merons, Neel type merons, and anti-merons, respectively. Combinations of twisting and heterostrain can further be exploited for engineering various electric polarization textures including 1D quasiperiodic lattices.

报告人简介

俞弘毅，2004年本科毕业于北大物理系，2010年博士毕业于中科院物理所，后进入香港大学物理系从事博士后和研究助理教授工作。2018年年底以海外高层次青年人才身份进入中山大学珠海校区物理与天文学院，任教授、博导。主要从事二维层状半导体材料的理论研究，亦多次参与与实验组的合作工作。已发表研究论文50余篇，Web of Science被引总数7600余次，入选科睿唯安评选的2021和2022年度交叉学科领域高被引科学家名单。

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