  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.
