Strong Field Optical Hall Effect in 2D Weyl Semimetal

Abstract: The study of interplay between the geometric nature of Bloch electrons and transverse responses under strong field offers new opportunities for optoelectronic applications. Here, we present a comprehensive study of the strong-field response of Weyl Dirac nodes in bilayer T'-WTe2 using time-dependent first-principles formalism. The electron dynamics is explored focusing on the mid-infrared frequency, ranging from the perturbative to nonperturbative regime. In the nonperturbative regime, the high-harmonic generation (HHG) spectra under a strong field clearly exhibit a plateau and energy cutoffs for both longitudinal and anomalous Hall (transverse) currents, with the latter being due to the large interband Berry curvature of the Weyl-Dirac semimetal. For the longitudinal harmonics, the intraband contributions increase with intensity, resulting in a complex interplay between interband polarization and intraband motions. Remarkably, if we take a comprehensive all-band perspective enabled by time-dependent density functional calculations, the anomalous Hall responses are purely attributed to the interband processes, even in the nonperturbative regime, thus Hall HHG can be crucial to understand the carrier dynamics. Our findings suggest that HHG associated with the ultrafast strong-field driven electron dynamics holds immense potential for exploring the nonlinear high Hall responses in Weyl semimetal.