Superconductivity in the infinite-layered nickelate (Nd,Sr)NiO₂ based on multiorbital model construction

The striking discovery of superconductivity in an infinite-layered nickelate (Nd,Sr)NiO₂[1] has attracted renewed interests in non-copper compounds. The mother compound NdNiO₂ has d⁹ electron configuration as in the high-T_c cuprates, but previous first-principles studies showed that the nickelate has narrower bandwidth than that of the cuprates, and there also exist additional electron-like Fermi pockets originating from the rare-earth 5d orbitals [2,3]. To investigate how these differences affect spin-fluctuation mediated superconductivity, we construct a seven-orbital model consisting of Ni 3d and rare-earth 5d orbitals by employing maximally localized Wannier functions and constrained random phase approximation. We apply fluctuation exchange approximation to the model to evaluate the strength of superconductivity. The calculation has revealed that much larger on-site interaction U than that of the cuprates suppresses T_c of d-wave superconductivity due to strong renormalization effects, while the additional Fermi pockets barely affect T_c [4]. [1] D. Li et al., Nature 572, 624 (2019). [2] V. I. Anisimsov et al., Phys. Rev. B 59, 7901 (1999). [3] K.-W. Lee and W. E. Pickett, Phys. Rev. B 70, 165109 (2004). [4] H. Sakakibara et al., arXiv:1909.00060 (2019).