A substantial hybridization between correlated Ni- d orbital and itinerant electrons in infinite-layer nickelates

The discovery of unconventional superconductivity in hole doped NdNiO2, similar to CaCuO2, has received enormous attention. However, different from CaCuO2, RNiO2 (R = Nd, La) has itinerant electrons in the rare-earth spacer layer. Previous studies show that the hybridization between Ni-$${d}_{{x}^{2}-{y}^{2}}$$ and rare-earth-d orbitals is very weak and thus RNiO2 is still a promising analog of CaCuO2. Here, we perform first-principles calculations to show that the hybridization between Ni-$${d}_{{x}^{2}-{y}^{2}}$$ orbital and itinerant electrons in RNiO2 is substantially stronger than previously thought. The dominant hybridization comes from an interstitial-s orbital rather than rare-earth-d orbitals, due to a large inter-cell hopping. Because of the hybridization, Ni local moment is screened by itinerant electrons and the critical UNi for long-range magnetic ordering is increased. Our work shows that the electronic structure of RNiO2 is distinct from CaCuO2, implying that the observed superconductivity in infinite-layer nickelates does not emerge from a doped Mott insulator. The discovery of superconductivity in doped NdNiO2 has generated excitement due to similarities with cuprates. Here, the authors use first-principles calculations to show that different from cuprates, a hybridization between Ni d-orbitals and itinerant electrons in NdNiO2 disfavours magnetism by screening Ni moment, as in Kondo systems.