Correlated electronic structure of the alternating single-layer bilayer nickelate La$_{5}$Ni$_{3}$O$_{11}$

The recent discovery of superconductivity under pressure in Ruddlesden-Popper (RP) nickelates has attracted a great deal of attention. Here, using density-functional theory plus dynamical mean-field theory, we study the correlated electronic structure of the latest superconducting member of the family: the alternating single-layer bilayer nickelate La$_{5}$Ni$_{3}$O$_{11}$. Due to its alternating single-layer and bilayer structural motif, this hybrid RP nickelate exhibits layer-selective physics with the single-layer neighboring a Mott instability, rendering the bilayer the dominant contributor to its low-energy physics, both at ambient and high pressure. The electronic structure of La$_{5}$Ni$_{3}$O$_{11}$ ultimately resembles that of the bilayer compound La$_{3}$Ni$_{2}$O$_{7}$, pointing to the presence of universal features in the family of superconducting RP nickelates. Thus, La$_{5}$Ni$_{3}$O$_{11}$ provides a new platform to disentangle the key degrees of freedom underlying superconductivity in pressurized RP nickelates, underscoring the central role of the bilayer structural motif.