Microscopic theory of superconducting phase diagram in infinite-layer nickelates

Abstract

Since the discovery of superconductivity in infinite-layer nickelates ${\mathrm{RNiO}}_{2}$ (R = La, Pr, Nd), great research efforts have been made to unveil its underlying superconducting mechanism. However, the physical origin of the intriguing hole-doped superconductivity phase diagram, characterized by a superconductivity dome sandwiched between two weak insulators, is still unclear. Here we present a microscopic theory for the electronic structure of nickelates from a fundamental model-based perspective. We found that the appearance of weak insulator phase in lightly and heavily hole-doped regime is dominated by Mottness and Hundness, respectively, exhibiting a unique orbital-selective doping originated from the competition of Hund interaction and crystal field splitting. Moreover, the superconducting phase can also be created in the ``mixed'' transition regime between Mott-insulator and Hund-induced correlated state, exactly reproducing the experimentally observed superconducting phase diagram. Our findings not only demonstrate the orbital-dependent strong-correlation physics in Ni $3d$ states but also provide a unified understanding of superconducting phase diagram in hole-doped infinite-layer nickelates, which are distinct from the well-established paradigms in cuprates and iron pnictides.