The interaction between intense laser pulses and atoms or molecules is a central topic in strong-field physics. By numerically solving the time-dependent Schrödinger equation (TDSE) under the single-active-electron approximation, we investigate the ultrafast electronic dynamics of an aligned ${\mathrm{N}}_2$ molecule at different internuclear distances driven by a circularly polarized extreme-ultraviolet laser. The results show that the photoelectron momentum distributions (PMDs) exhibit a four-lobe structure which can be explained by the attosecond perturbation theory. As the internuclear distance increases, the intensities of PMDs, ionization probabilities, electron currents, and ultrafast magnetic-field strengths all decrease, primarily attributed to the reduced coupling strength between the initial state and the continuum state. Notably, the electron current generated from the highest occupied molecular orbital (HOMO) is 1 order of magnitude stronger than that of HOMO−1. The ultrafast magnetic field oscillates along the axial direction when the initial state is the HOMO, whereas it rotates in the plane when the initial state is the HOMO−1. Furthermore, we employ a deep-learning technique to predict the ultrafast magnetic field, achieving more than $98\%$ agreement between model predictions and TDSE results.

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• Atomic & molecular structure
• Light-matter interaction
• Single- and few-photon ionization & excitation
• Ultrafast optics
• Molecules
• Schroedinger equation