Neufeld Ofer, Hübener Hannes, Jotzu Gregor, De Giovannini Umberto, Rubio Angel
Center for Free-electron Laser Science, Max Planck Institute for the Structure and Dynamics of Matter, Hamburg 22761, Germany.
Dipartimento di Fisica e Chimica─Emilio Segrè, Università degli Studi di Palermo, Palermo I-90123, Italy.
Nano Lett. 2023 Aug 23;23(16):7568-7575. doi: 10.1021/acs.nanolett.3c02139. Epub 2023 Aug 14.
We study low-frequency linearly polarized laser-dressing in materials with valley (graphene and hexagonal-Boron-Nitride) and topological (Dirac- and Weyl-semimetals) properties. In Dirac-like linearly dispersing bands, the laser substantially moves the Dirac nodes away from their original position, and the movement direction can be fully controlled by rotating the laser polarization. We prove that this effect originates from band nonlinearities away from the Dirac nodes. We further demonstrate that this physical mechanism is widely applicable and can move the positions of the valley minima in hexagonal materials to tune valley selectivity, split and move Weyl cones in higher-order Weyl semimetals, and merge Dirac nodes in three-dimensional Dirac semimetals. The model results are validated with ab initio calculations. Our results directly affect efforts for exploring light-dressed electronic structure, suggesting that one can benefit from band nonlinearity for tailoring material properties, and highlight the importance of the full band structure in nonlinear optical phenomena in solids.
我们研究了具有能谷特性（石墨烯和六方氮化硼）和拓扑特性（狄拉克半金属和外尔半金属）的材料中的低频线性偏振激光修饰。在类狄拉克线性色散能带中，激光会使狄拉克节点大幅偏离其原始位置，并且通过旋转激光偏振可以完全控制其移动方向。我们证明，这种效应源于远离狄拉克节点的能带非线性。我们进一步证明，这种物理机制具有广泛的适用性，它可以移动六方材料中能谷极小值的位置以调节能谷选择性，在高阶外尔半金属中分裂并移动外尔锥，以及在三维狄拉克半金属中合并狄拉克节点。模型结果通过从头算计算得到了验证。我们的结果直接影响探索光修饰电子结构的研究工作，表明人们可以利用能带非线性来定制材料特性，并突出了完整能带结构在固体非线性光学现象中的重要性。
