Revealing electronic correlations in YNi₂B₂C using photoemission spectroscopy

The low-energy electronic structure of materials is crucial to understanding and modeling their physical properties. Angle-resolved photoemission spectroscopy (ARPES) is the best experimental technique to measure this electronic structure, but its interpretation can be delicate. Here we use a combination of density functional theory (DFT) and one-step model of photoemission to decipher the soft x-ray ARPES spectra of the quaternary borocarbide superconductor YNi₂B₂C. Our analysis reveals the presence of moderate electronic correlations beyond the semilocal DFT within the generalized gradient approximation. We show that DFT and the full potential Korringa-Kohn-Rostoker method combined with the dynamical mean field theory (DFT+DMFT) with average Coulomb interaction U = 3.0 eV and the exchange energy J = 0.9 eV applied to the Ni d-states are necessary for reproducing the experimentally observed SX-ARPES spectra.