近日，美国伊利诺伊大学厄巴纳-香槟分校的Fahad Mahmood及其研究团队取得一项新进展。他们实现了拓扑反铁磁体中狄拉克能隙的弗洛凯-布洛赫操纵。相关研究成果已于2025年1月21日在国际知名学术期刊《自然—物理学》上发表。

该研究团队实现了对拓扑反铁磁体MnBi₂Te₄中，狄拉克表面态质量的弗洛凯-布洛赫操纵。利用时间分辨和角度分辨光电子能谱技术，研究人员发现，尽管平衡状态下的狄拉克锥是无质量的，但中红外圆偏振光的不同旋向会导致反铁磁相中，出现截然不同的狄拉克质量能隙。

研究人员用具有随机质量的狄拉克费米子来解释这一发现。这项研究结果凸显了弗洛凯-布洛赫操纵作为一种强大工具，即使在存在无序的情况下，也能有效控制材料的拓扑性质，并揭示那些可能逃避传统探测手段的材料特性。

据悉，通过周期性激光脉冲驱动材料实现的弗洛凯-布洛赫操纵，是一种能够有效改变固体电子能带结构，从而工程化其电子和磁性相的方法。然而，弗洛凯-布洛赫操纵在拓扑磁性系统，尤其是具有本征无序性的系统中的应用，仍有待探索。

附：英文原文

Title: Floquet–Bloch manipulation of the Dirac gap in a topological antiferromagnet

Author: Bielinski, Nina, Chari, Rajas, May-Mann, Julian, Kim, Soyeun, Zwettler, Jack, Deng, Yujun, Aishwarya, Anuva, Roychowdhury, Subhajit, Shekhar, Chandra, Hashimoto, Makoto, Lu, Donghui, Yan, Jiaqiang, Felser, Claudia, Madhavan, Vidya, Shen, Zhi-Xun, Hughes, Taylor L., Mahmood, Fahad

Issue&Volume: 2025-01-21

Abstract: Floquet–Bloch manipulation, achieved by driving a material periodically with a laser pulse, is a method that enables the engineering of electronic and magnetic phases in solids by effectively modifying the structure of their electronic bands. However, the application of Floquet–Bloch manipulation in topological magnetic systems, particularly those with inherent disorder, remains largely unexplored. Here we realize Floquet–Bloch manipulation of the Dirac surface-state mass of the topological antiferromagnet MnBi₂Te₄. Using time- and angle-resolved photoemission spectroscopy, we show that opposite helicities of mid-infrared circularly polarized light result in substantially different Dirac mass gaps in the antiferromagnetic phase, despite the equilibrium Dirac cone being massless. We explain our findings in terms of a Dirac fermion with a random mass. Our results underscore Floquet–Bloch manipulation as a powerful tool for controlling topology, even in the presence of disorder, and for uncovering properties of materials that may elude conventional probes.

DOI: 10.1038/s41567-024-02769-6

Source: https://www.nature.com/articles/s41567-024-02769-6