Probing photoexcited states in infinite-layer nickelates with time-resolved RIXS

The infinite-layer nickelates, RENiO₂, RE=La, Nd, Pr, offer a novel platform to study the nature of high T_c superconductivity and the normal state from which it emerges. Bearing a strong resemblance to the cuprate superconductors, strong correlations play an important role in shaping the electronic and magnetic properties of the 3d^₉ nickelates. The electronic structure of the nickelates is thought to deviate from that of the cuprates, however, most notably in the multi-orbital nature of the fermi surface -- including both nickel 3d and rare earth 5d states. Ultrafast photoexcitation presents a new pathway to manipulate the electronic properties of these nickelates and engineer new states in this system. In this talk we will discuss photo-induced phenomena in the infinite-layer nickelates (Nd,Sr)NiO₂ using time-resolved resonant inelastic x-ray scattering (trRIXS) and x-ray absorption spectroscopy (trXAS). We study the ultrafast electronic dynamics of d⁹ and d^8.8 nickelates on the 100 fs timescale, examining the response of both magnetic and crystal-field excitations when the system is driven out-of-equilibrium.