Electronic structure of rare-earth infinite-layer RNiO₂(R=La,Nd)

Abstract

The discovery of infinite-layer nickelate superconductor marks the new era in the field of superconductivity. In the rare-earth (R) ickelates RNiO₂, although the Ni is also of d⁹ electronic configuration, analogous to Cu d⁹ in cuprates, whether electronic structures in infinite-layer nickelate are the same as cuprate and possess the single-band feature as well are still open questions. To illustrate the electronic structure of rare-earth infinite-layer nickelate, we perform first-principles calculations of LaNiO₂ and NdNiO₂ compounds and compare them with that of CaCuO₂ using the hybrid functional method together with Wannier projection and group symmetry analysis. Our results indicate that the Ni dₓ²₋ᵧ² in the LaNiO₂ has weak hybridization with other orbitals and exhibits the characteristic single-band feature, whereas in NdNiO₂, the Nd f orbital hybridizes with Ni dₓ²₋ᵧ² and is a non-negligible ingredient for transport and even high-temperature superconductivity. Given that the Cu dₓ²₋ᵧ² in cuprate strongly hybridizes with O 2p, the calculated band structures of nickelate imply some new band characters, which is worthy of more attention.