Multi-timescale ultrafast dynamics in multiferroic NiI₂

Multiferroic materials have drawn a considerable amount of research attention in terms of their formation mechanisms and ferroic orderings characterization. In the context of applications that rely on dynamical control of ferroic ordering, research on non-equilibrium dynamics of the multiferroics is critical. Charge and magnetic ordering often arise from local perturbations which can respond to light on ultrafast timescales. Further, for a more comprehensive understanding, element-selective probing helps decode the intricate relationships and interplay among the material's constituents. Here, we study photoinduced ultrafast dynamics on NiI₂, a multiferroic material which has recently been reported to have multiferroic properties down to the monolayer limit, using table-top extreme-ultraviolet attosecond transient absorption spectroscopy. Leveraging the elemental sensitivity and few-femtosecond time resolution, ultrafast photoinduced electronic and structural dynamics are measured on iodine and nickel separately and simultaneously. In the electronic system of iodine, photoinduced dynamics are observed to begin abruptly and evolve on a timescale of tens of femtoseconds. Meanwhile, nickel seems to primarily respond through structural distortion after a few hundred femtoseconds. The contrast in the observed dynamics provides insights into the coupling between different ferroic orderings and paves the way for creating emerging functionalities on multiferroic materials.