The Mottness and the Anderson localization in bilayer nickelate La$_3$Ni$_2$O$_{7-δ}$

Abstract: The oxygen content plays a pivotal role in determining the electronic properties of the recently discovered La$3$Ni$_2$O${7-\delta}$ superconductors. In this work, we investigate the impact of oxygen vacancies on the insulating behavior of La$3$Ni$_2$O${7-\delta}$ across the doping range $\delta = 0$ to $0.5$. At $\delta = 0.5$, we construct a bilayer Hubbard model to describe the system. Using dynamical mean-field theory, we demonstrate that the model captures the characteristics of a bilayer Mott insulator. To explore the effects of disorder within the range $\delta = 0$ to $0.5$, we treat the system as a mixture of metallic and Mott insulating phases. By analyzing the geometric average of the local density of states, we identify an Anderson localization transition occurring around $\delta \sim 0.2$. These results provide a quantitative explanation of recent experimental observations and highlight the critical influence of oxygen content on the physical properties of La$3$Ni$_2$O${7-\delta}$.