清华大学周树云研究组报道了黑磷中的赝自旋选择性Floquet带工程。相关论文于2023年2月1日发表在《自然》杂志上。

在时间和角度分辨的光电发射光谱测量的基础上，该团队报告了一种模型半导体黑磷的Floquet带工程的实验特征。在340-440 meV光子能量的近共振泵浦中，在带边附近观察到强的带重整化现象。特别是，在共振点上解决了光诱导的动态间隙开放，这与Floquet边带同时出现。

此外，带重整化显示了沿扶手椅方向倾向于泵浦极化的强烈选择规则，这表明由晶格对称性强制的Floquet带工程的赝自旋选择性。他们的工作证明了黑磷的赝自旋选择性Floquet带工程，为半导体Floquet工程提供了重要的指导原则。

据悉，时间周期光场已成为控制固态材料、冷原子和光子系统中的量子态的一个控制按钮，方法是在强耦合极限下与被光子修饰的Floquet态杂交，被称为Floquet工程。这种相互作用导致量子材料的定制性质，例如，狄拉克材料的拓扑性质的修改和光学响应的调制。尽管在过去的十年中有广泛的研究兴趣，但没有实验证据表明半导体的动量分辨Floquet带工程，这是将Floquet工程扩展到广泛的固态材料的关键一步。

附：英文原文

Title: Pseudospin-selective Floquet band engineering in black phosphorus

Author: Zhou, Shaohua, Bao, Changhua, Fan, Benshu, Zhou, Hui, Gao, Qixuan, Zhong, Haoyuan, Lin, Tianyun, Liu, Hang, Yu, Pu, Tang, Peizhe, Meng, Sheng, Duan, Wenhui, Zhou, Shuyun

Issue&Volume: 2023-02-01

Abstract: Time-periodic light field has emerged as a control knob for manipulating quantum states in solid-state materials1,2,3, cold atoms4 and photonic systems5 through hybridization with photon-dressed Floquet states6 in the strong-coupling limit, dubbed Floquet engineering. Such interaction leads to tailored properties of quantum materials7,8,9,10,11, for example, modifications of the topological properties of Dirac materials12,13 and modulation of the optical response14,15,16. Despite extensive research interests over the past decade3,8,17,18,19,20, there is no experimental evidence of momentum-resolved Floquet band engineering of semiconductors, which is a crucial step to extend Floquet engineering to a wide range of solid-state materials. Here, on the basis of time and angle-resolved photoemission spectroscopy measurements, we report experimental signatures of Floquet band engineering in a model semiconductor, black phosphorus. On near-resonance pumping at a photon energy of 340–440meV, a strong band renormalization is observed near the band edges. In particular, light-induced dynamical gap opening is resolved at the resonance points, which emerges simultaneously with the Floquet sidebands. Moreover, the band renormalization shows a strong selection rule favouring pump polarization along the armchair direction, suggesting pseudospin selectivity for the Floquetband engineering as enforced by the lattice symmetry. Our work demonstrates pseudospin-selective Floquet band engineering in black phosphorus and provides important guiding principles for Floquet engineering of semiconductors.

DOI: 10.1038/s41586-022-05610-3

Source: https://www.nature.com/articles/s41586-022-05610-3