Correlated spin and charge dynamics during ultrafast demagnetization of Ca₂RuO₄

The multiband Mott insulator Ca₂RuO₄ has recently been reported to host an exotic antiferromagnetic ground state with excitonic character. Using magnetic field dependent time-resolved second harmonic generation polarimetry, we demonstrate an ultrafast photo-doping induced collapse of the antiferromagnetic state in Ca₂RuO₄. Simultaneous transient reflectivity measurements reveal that relaxation pathways of photo-dopants are intimately correlated with the dynamical evolution of the antiferromagnetic order parameter. Possible connections of our observation to the theoretical proposal of excitonic magnetism will be discussed.