Dynamical axion state with hidden pseudospin Chern numbers in MnBi2Te4 -based heterostructures

作者：Huaiqiang Wang, Dinghui Wang, Zhilong Yang, Minji Shi, Jiawei Ruan, Dingyu Xing, Jing Wang, Haijun Zhang · 发表于：Physical review. B./Physical review. B · 年份：2020 · DOI：10.1103/physrevb.101.081109 · 被引用次数：47 · 研究领域：Topological Materials and Phenomena、Advanced Condensed Matter Physics、Quantum many-body systems

An axion is a hypothetical elementary particle which was initially postulated to solve the charge conjugation-parity problem in particle physics. Interestingly, the axion state has emerged in the effective theory of topological insulators and has attracted extensive attention in condensed matter physics. Time-reversal or inversion symmetry constrains the axion field $\ensuremath{\theta}$ to be quantized. When both the time-reversal and inversion symmetries are broken by, say, an antiferromagnetic order, the axion field $\ensuremath{\theta}$ could become unquantized and dynamical along with magnetic fluctuations, which is termed the dynamical axion field. Here, we reveal that a wide class of topological-insulator-based dynamical axion states could be distinguished from the normal-insulator-based ones by a hidden quantity derived from the pseudospin Chern number. Motivated by recent research on the ${\mathrm{MnBi}}_{2}{\mathrm{Te}}_{4}$ family of materials, we further show that such topological-insulator-based dynamical axion states can be hopefully achieved in ${\mathrm{MnBi}}_{2}{\mathrm{Te}}_{4}$-based heterostructures, which should greatly facilitate the study of axion electrodynamics in condensed matter physics.