主讲人：栗宇航，加州大学河滨分校博士后
时 间：2023年11月1日 19:00
地 点：研究生院D104
联系人：曾犟
讲座摘要：Axion insulator possesses a quantized axion field θ=π protected by combined lattice and time-reversal symmetry, holding great potentials for 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.
主讲人简介：栗宇航，1990年9月生，2013年本科毕业于四川大学物理学基地班，2018年博士毕业于北京大学量子材料科学中心，并荣获北京大学优秀毕业生，导师谢心澄院士。2019年1月至今在加州大学河滨分校从事博士后研究工作。目前主要从事磁性材料和拓扑材料的理论研究。近年来以第一作者身份发表SCI论文10篇，包括Phys. Rev. Lett. 1篇、npj Quantum Materials 1篇、Phys. Rev. Research 2篇、Phys. Rev. B 4篇。
