Warshauer - Nonequilibrium exploration of an excitonic antiferromagnet through targeted ultrafast optical excitation

Correlated materials provide rich platforms through which to access interesting nonequilibrium states using the pathways provided by the interaction of spin, orbit, charge, and lattice degrees of freedom. Ultrafast laser pulses allow us to disentangle the transient dynamics of these nonequilibrium states and potentially open the door to tunable control of material phases. Van der Waals magnets are a particularly interesting material family for investigating light-matter interactions. Exploring the nature of the spin-orbit entangled exciton series of the van der Waals antiferromagnet NiPS3, we find a long-lived, photo-induced state with features characteristic of population inversion. Additionally, we apply our photoexcitation scheme in bulk NiPS3 to analyze photocarrier densities, estimating the bandgap and spin-orbit entangled exciton binding energy. These results provide key insights into the electronic and excitonic characteristics of NiPS3 and reveal a useful nonequilibrium state generated through targeted photoexcitation in correlated materials.