Light-wave-controlled Haldane model in monolayer hexagonal boron nitride

• 成果类型: Article
• 署名作者: Mitra, Sambit; Jimenez-Galan, Alvaro; Aulich, Mario; Neuhaus, Marcel; Silva, Rui E. F.; Pervak, Volodymyr; Kling, Matthias F.; Biswas, Shubhadeep
• 署名单位: University of Munich; Consejo Superior de Investigaciones Cientificas (CSIC); CSIC - Instituto de Ciencia de Materiales de Madrid (ICMM); Leibniz Association; Max Born Institute for Nonlinear Optics & Short Term Spectroscopy; Stanford University; United States Department of Energy (DOE); SLAC National Accelerator Laboratory; Stanford University
• 刊物名称: Nature
• ISSN/ISSBN: 0028-6502
• DOI: 10.1038/s41586-024-07244-z
• 发表日期: 2024-04-25
• 页码: 752-+
• 关键词: valley polarization; mos2; superconductivity; valleytronics; realization

摘要

In recent years, the stacking and twisting of atom-thin structures with matching crystal symmetry has provided a unique way to create new superlattice structures in which new properties emerge(1,2). In parallel, control over the temporal characteristics of strong light fields has allowed researchers to manipulate coherent electron transport in such atom-thin structures on sublaser-cycle timescales(3,4). Here we demonstrate a tailored light-wave-driven analogue to twisted layer stacking. Tailoring the spatial symmetry of the light waveform to that of the lattice of a hexagonal boron nitride monolayer and then twisting this waveform result in optical control of time-reversal symmetry breaking(5) and the realization of the topological Haldane model(6) in a laser-dressed two-dimensional insulating crystal. Further, the parameters of the effective Haldane-type Hamiltonian can be controlled by rotating the light waveform, thus enabling ultrafast switching between band structure configurations and allowing unprecedented control over the magnitude, location and curvature of the bandgap. This results in an asymmetric population between complementary quantum valleys that leads to a measurable valley Hall current(7), which can be detected by optical harmonic polarimetry. The universality and robustness of our scheme paves the way to valley-selective bandgap engineering on the fly and unlocks the possibility of creating few-femtosecond switches with quantum degrees of freedom.