Magnetic and f-electron effects in LaNiO2 and NdNiO2 nickelates with cuprate-like 3{d}_{{x}^{2}-{y}^{2}} band

Ruiqi Zhang,Jianwei Sun,Christopher Lane,Arun Bansil,Bernardo Barbiellini,Robert S Markiewicz,Bahadur Singh,Johannes Nokelainen

doi:10.1038/s42005-021-00621-4

Abstract

Recent discovery of superconductivity in the doped infinite-layer nickelates has renewed interest in understanding the nature of high-temperature superconductivity more generally. The low-energy electronic structure of the parent compound NdNiO2, the role of electronic correlations in driving superconductivity, and the possible relationship between the cuprates and the nickelates are still open questions. Here, by comparing LaNiO2 and NdNiO2 systematically within a parameter-free, all-electron first-principles density-functional theory framework, we reveal the role of Nd 4f electrons in shaping the ground state of pristine NdNiO2. Strong similarities are found between the electronic structures of LaNiO2 and NdNiO2, except for the effects of the 4f electrons. Hybridization between the Nd 4f and Ni 3d orbitals is shown to significantly modify the Fermi surfaces of various magnetic states. In contrast, the competition between the magnetically ordered phases depends mainly on the gaps in the Ni 3{d}_{{x}^{2}-{y}^{2}} band. Our estimated value of the on-site Hubbard U in the nickelates is similar to that in the cuprates, but the value of the Hund’s coupling JH is found to be sensitive to the Nd magnetic moment. In contrast with the cuprates, NdNiO2 presents 3D magnetism with competing antiferromagnetic and (interlayer) ferromagnetic exchange, which may explain why the Tc is lower in the nickelates.

Highlights

Recent discovery of superconductivity in the doped infinite-layer nickelates has renewed interest in understanding the nature of high-temperature superconductivity more generally
NdNiO2, which could partly be a signature of short-range magnetic fluctuations due to the intrinsic off-stoichiometry produced by the inhomogeneous oxygen deintercalation crystal-growth process[7]
We present a systematic in-depth study of the electronic and magnetic structures of both LaNiO2 and NdNiO2 using the strongly-constrained-and-appropriately-normed (SCAN) density functional[36] with spin–orbit coupling to examine the effects of f electron physics

Summary

Introduction

Recent discovery of superconductivity in the doped infinite-layer nickelates has renewed interest in understanding the nature of high-temperature superconductivity more generally. NdNiO2, which could partly be a signature of short-range magnetic fluctuations due to the intrinsic off-stoichiometry produced by the inhomogeneous oxygen deintercalation crystal-growth process[7] In this connection, a variety of theoretical studies have been performed to understand the low-energy physics of the nickelates employing density functional theory (DFT)[14,18,24,25,26] and “beyond” DFT methods such as DFT+U18,27,28, quasiparticle GW29, dynamical mean-field theory (DMFT)[27,30,31,32], and model Hamiltonians[15,17,27,33] that have been constructed to understand the low-energy physics. These calculations neglect the effects of spin–orbit coupling (SOC) crucial for capturing the correct fband splittings, and required the introduction and fine tuning of external ad hoc parameters such as the Hubbard U and the exactexchange admixture, limiting their predictive power[35]

Methods

Results

Conclusion