Electronic Structure Trends Across the Rare-Earth Series in Superconducting Infinite-Layer Nickelates

The recent discovery of superconductivity in oxygen-reduced monovalent nickelates has raised a new platform for the study of unconventional superconductivity, with similarities to and differences from the cuprate high-temperature superconductors. In this paper, we investigate the family of infinite-layer nickelates RNiO2 with rare-earth R spanning across the lanthanide series, introducing a new and nontrivial knob with which to tune nickelate superconductivity. When traversing from La to Lu, the out-of-plane lattice constant decreases dramatically with an accompanying increase of Ni d(x2-y2) bandwidth; however, surprisingly, the role of oxygen charge transfer diminishes. In contrast, the magnetic exchange grows across the lanthanides, which may be favorable to superconductivity. Moreover, compensation effects from the itinerant 5d electrons present a closer analogy to Kondo lattices, indicating a stronger interplay between charge transfer, bandwidth renormalization, compensation, and magnetic exchange. We also obtain the microscopic Hamiltonian using the Wannier downfolding technique, which will provide the starting point for further many-body theoretical studies.

Automated summary

This paper investigates the infinite-layer nickelates RNiO2 with rare-earth R spanning across the lanthanide series, providing a new knob for tuning nickelate superconductivity. The study shows that there are significant changes in lattice constants, bandwidth, magnetic exchange, and compensation effects across the lanthanides, suggesting their potential impact on superconductivity.