Charge and Spin Order Dichotomy in NdNiO2 Driven by the Capping Layer

Superconductivity in infinite-layer nickelates holds exciting analogies with that of cuprates, with similar structures and 3d-electron count. Using resonant inelastic x-ray scattering, we studied electronic and magnetic excitations and charge density correlations in Nd1???xSrxNiO2 thin films with and without an SrTiO3 capping layer. We observe dispersing magnons only in the capped samples, progressively dampened at higher doping. We detect an elastic resonant scattering peak in the uncapped x = 0 compound at wave vector (-1/3; 0), remindful of the charge order signal in hole doped cuprates. The peak weakens at x = 0.05 and disappears in the superconducting x = 0.20 film. The role of the capping on the electronic reconstruction far from the interface remains to be understood.