Dynamic control of electron correlations in photodoped charge-transfer insulators.

The electronic properties of correlated insulators are governed by the strength of Coulomb interactions, enabling the control of electronic conductivity with external stimuli. This work highlights that the strength of electronic correlations in nickel oxide (NiO), a prototypical charge-transfer insulator, can be coherently reduced by tuning the intensity of an optical pulse excitation. This weakening of correlations persists for hundreds of picoseconds and exhibits a recovery time independent of photodoping density across two orders of magnitude. A broadening of the charge-transfer gap is also observed, consistent with dynamical screening. The high degree of control achieved over both the energy and temporal dynamics of electronic correlations offers a promising avenue to a full optical control of correlated systems and the Mott transition.