【时  间】 2月27日（周二） 下午 14:00

【地  点】 量子院526报告厅

【主  持】 张泼（半导体自旋与拓扑量子计算团队副研究员）

【题  目】 Axion physics in condensed matter systems

【摘  要】Axion insulator possesses a quantized axion field θ=π protected by combined lattice and time-reversal symmetry, holding great potentials or device applications in layertronics and quantum computing. Although some experiments hinted that MnBi₂Te₄ is a possible candidate as theoretical prediction, the direct evidence for this exotic state remains elusive. We propose a MnBi₂Te₄ tunnel junction, in which the axion insulator phase can be unambiguously determined by the quantized current induced by a harmonic magnetic field. On the other hand, we extend this axion insulator to the high spin case and thus propose a high spin axion insulator defined on spin-s representation. Moreover, when both time-reversal and space inversion symmetries are absent, a new kind of materials termed dynamic axion insulator with a temporal dependent axion field can emerge in the presence of antiferromagnetic resonance. We show that a dynamic axion insulator Josephson junction exhibits a striking doubled Shapiro steps in the presence of a dc bias and a static magnetic field, which furnishes a hallmark for the dynamic axion insulator. Our work enriches the understanding of axion insulator in condensed matter systems, paving the way for future device applications.  

References: 

[1]. Yu-Hang Li and Ran Cheng, Physical Review Research 4, L022067(2022) 

[2]. Yu-Hang Li, Hua Jiang and X. C. Xie, to appear 

[3]. Shuai Li, Ming Gong, Yu-Hang Li, Hua Jiang and X. C. Xie, to appear 

【报告人简介】Prof. Yuhang Li is currently an associate professor at Nankai University. He received his bachelor degree from Sichuan University in 2013, and earned his Ph.D from International Center for Quantum Materials at Peking university in 2018. After that, he spent five years as a postdoctoral scholar at University of California, Riverside. He joined Nankai University from January 2024. His research interests foc.