Cornertronics in Two-Dimensional Second-Order Topological Insulators

作     者：Yilin Han Chaoxi Cui Xiao-Ping Li Ting-Ting Zhang Zeying Zhang Zhi-Ming Yu Yugui Yao 

作者机构：Centre for Quantum Physics Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurement (MOE) School of Physics Beijing Key Lab of Nanophotonics and Ultrafine Optoelectronic Systems School of Physics School of Physical Science and Technology Beijing National Laboratory for Condensed Matter Physics Institute of Physics College of Mathematics and Physics 

出 版 物：《Physical Review Letters》 (Phys Rev Lett)

年 卷 期：2024年第133卷第17期

页      面：176602页

核心收录：

学科分类：07[理学] 0702[理学-物理学] 

基　　金：National Key Research and Development Program of China, NKRDPC, (2020YFA0308800) National Key Research and Development Program of China, NKRDPC National Natural Science Foundation of China, NSFC, (12234003, 12321004, 12304086, 12004035) National Natural Science Foundation of China, NSFC 

主　　题：Electrical properties First-principles calculations Topological materials Quantum dots 

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 posses 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 corner-layer 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.