报告人：余智明教授   北京理工大学
邀请人：高淼 教授
报告时间：2025年5月20日（周二）， 9：30
报告地点：龙赛理科楼314会议室 

报告人简介：余智明，北京理工大学教授，博士毕业于中国人民大学物理系，曾在北京理工大学、新加坡科技设计大学进行博士后研究。主要以对称性理论为研究工具，系统探索新型量子材料中的新材料、新机制和新应用。当前的研究兴趣包括：拓扑物态、新型磁性和二维材料、多自由度耦合、界面散射、和霍尔输运等方向。发表SCI论文100余篇，H指数46。2019年底回国工作后发表通讯/一作文章包括8篇PRL、2篇Nat. Commun.、2篇Sci. Bull.等。
 
报告摘要： 
Traditional electronic devices rely on the electron’s intrinsic degrees of freedom (d.o.f.) to process information. However, additional d.o.f., like the valley, can emerge in the low-energy states of certain systems. Here, we show that the quantum dots constructed from two-dimensional second-order topological insulators possess a new kind of d.o.f., namely corner freedom, related to the topological corner states that reside at different corners of the systems. Since the corner states are well separated in real space, they can be individually and intuitively manipulated, giving rise to the concept of cornertronics. Via symmetry analysis and material search, we identify the TiSiCO-family monolayers as the first prototype of cornertronics materials, where the corner states can be controlled by both electric and optical fields due to novel cornerlayer coupling effect and corner-contrasted linear dichroism. Furthermore, we find that the band gap of the TiSiCO nanodisk lies in the terahertz region and is robust to size reduction. These results indicate that the TiSiCO nanodisks can be used to design terahertz devices with ultrasmall size and electric-field tunable band gap. Besides, the TiSiCO nanodisks are simultaneously sensitive to both the strength and polarization of the terahertz waves. Our findings not only pave the way for cornertronics, but also open a new direction for research in two-dimensional second-order topological insulators, quantum dots, and terahertz electronics. 

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