Screening of atomic excitations in Sr₂RuO₄ observed by temperature-dependent ARPES

Sr₂RuO₄ is one of the most studied unconventional superconductors, but the symmetry of its superconducting order parameter remains unresolved. Determining the pairing mechanism requires a detailed understanding of the strongly correlated normal state from which superconductivity emerges. Sr₂RuO₄ shows an incoherent-coherent crossover into a Fermi liquid with enhanced effective masses at low-temperatures. The multiorbital, correlated nature is interpreted as Hund’s metal physics created by an interplay between Coulomb and Hund’s rule interactions. We employ angle-resolved photoemission spectroscopy (ARPES) to study the temperature evolution of the spectral function in the normal state of Sr₂RuO₄. Expanding previous ARPES studies, we perform a detailed spectral weight analysis at both low and high binding energies up to 11eV. Upon lowering the temperature, we observe an increase of the quasiparticle spectral weight. Simultaneously, the intensity decreases in the incoherent part of the spectral function in an energy window that coincides with the predicted range of Hubbard bands. We will compare our ARPES data to DFT and DMFT calculations. We interpret our results as a spectral weight transfer due to screening of atomic excitations, that drives the formation of a correlated Fermi liquid in line with a Hund’s metal picture.