Tunable dynamical magnetoelectric effect in antiferromagnetic topological insulator MnBi2Te4 films
Tunable dynamical magnetoelectric effect in antiferromagnetic topological insulator MnBi2Te4 films
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DOI：
10.1038/s41524-021-00589-3
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发表时间：
2020-10
影响因子：
9.7
通讯作者：
Tongshuai Zhu;Huaiqiang Wang;Haijun Zhang;D. Xing
中科院分区：
文献类型：
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作者：
Tongshuai Zhu;Huaiqiang Wang;Haijun Zhang;D. Xing
轴子被假设为基本粒子，以解决强电荷共轭和宇称难题，后来轴子也被认为是宇宙中暗物质的可能组成部分。然而，自然界中轴子的存在尚未得到证实。有趣的是，轴子产生于源自凝聚态物理学陈-西蒙斯理论的赝标量场。在反铁磁绝缘体中，轴子场可以由于自旋波激发而变得动态，并表现出丰富的奇异现象，例如轴子极化激元。然而，反铁磁动态轴子绝缘体尚未在现实材料中得到实验鉴定。最近，MnBi2Te4被发现是一种反铁磁拓扑绝缘体，具有受反演对称性和磁晶对称性保护的量子化静态轴子场。在这里，我们研究了对称性自发破缺的 MnBi2Te4 薄膜，发现通过调整 MnBi2Te4 薄膜的厚度、温度或元素替代可以显着增强动态磁电效应。我们的结果表明，MnBi2Te4 和相关化合物的薄膜可以为轴子电动力学的实验研究提供一个有前途的材料平台。
Axion was postulated as an elementary particle to solve the strong charge conjugation and parity puzzle, and later axion was also considered to be a possible component of dark matter in the universe. However, the existence of axions in nature has not been confirmed. Interestingly, axions arise out of pseudoscalar fields derived from the Chern–Simons theory in condensed matter physics. In antiferromagnetic insulators, the axion field can become dynamical due to spin-wave excitations and exhibits rich exotic phenomena, such as axion polariton. However, antiferromagnetic dynamical axion insulator has yet been experimentally identified in realistic materials. Very recently, MnBi2Te4was discovered to be an antiferromagnetic topological insulator with a quantized static axion field protected by inversion symmetryand magnetic-crystalline symmetry. Here, we studied MnBi2Te4films in which both theandsymmetries are spontaneously broken and found that substantially enhanced dynamical magnetoelectric effects could be realized through tuning the thickness of MnBi2Te4films, temperature, or element substitutions. Our results show that thin films of MnBi2Te4and related compounds could provide a promising material platform to experimentally study axion electrodynamics.