Time:  10:00 am, March 26th, 2021

Speaker: Dr. Yinong Zhou, University of Utah

Abstract:

Topology, a mathematical concept, was first introduced to solid-state physics in the early ’80s to explain the quantum Hall effect (QHE). The discovery of topological insulator (TI) a decade ago, which hosts metallic edge or surface states while its bulk behaves as an insulator, has opened a new area of topological physics. Following the study of TI, other topological phases have been discovered, e.g., Dirac/Weyl semimetal, which has linear band dispersion along all directions. In recent years, the presence of topological flat band adds another dimension to topological physics. The dispersionless topological flat band arises from destructive interference of Bloch wavefunctions and is independent of the single-particle crystal Hamiltonian. The completely quenched electronic kinetic energy in a flat band magnifies any finite electron-electron interaction. The phase cancelation renders the flat band to be inherently topologically non-trivial, leading to a range of exotic quantum phases, such as high-temperature superconductivity, ferromagnetism, fractional QHE, and TI phase. In this talk, I will introduce several new phenomena of topological Dirac and flat-band materials, including Weyl points created by a 3D flat band, excited-state quantum anomalous/spin Hall effect arises from enantiomorphic flat bands, giant intrinsic circular dichroism originated by enantiomorphic flat Chern bands, and Dirac Mott insulator and circular dichroism Hall effect in the antiferromagnetic superatomic graphene.

Reference:

[1] Y. Zhou, K.H. Jin, H. Huang, Z. Wang, and Feng Liu, Phys. Rev. B., 99, 201105(R) (2019).

[2] Y. Zhou, G. Sethi, H. Liu, and F. Liu, arXiv:1908.03689 (2019).

[3] Y. Zhou, G. Sethi, C. Zhang, X. Ni, and Feng Liu, Phys. Rev. B., 102, 125115 (2020).

[4] Y. Zhou, and F. Liu, Nano Lett. 21.1: 230-235 (2021).

Brief CV of Dr. Yong-Chang Lau:

Yinong Zhou is currently a Ph.D. candidate advised by Prof. Feng Liu in the Department of Materials Science & Engineering at the University of Utah. She received her B.S. degree in physics at the University of Science and Technology of China in 2016. She has been working on modeling and simulation of properties of topological materials.

Click to view the recorded report video►http://as.iphy.ac.cn/video_detail.php?id=28586