Spin excitations in Nd1-xSrxNiO2 and YBa2Cu3O7-delta: the influence of Hubbard U

TL;DR

This study compares magnetic excitations in nickelates and cuprates using RIXS, revealing the impact of Hubbard U on their magnetic properties and doping behaviors, with implications for understanding high-temperature superconductivity.

Contribution

It introduces a Hubbard-based model to explain the doping-dependent magnetic excitations and highlights the larger U in nickelates compared to cuprates.

Findings

U is about twice larger in nickelates than in cuprates.

Magnetic bandwidth decreases upon doping in nickelates.

The dominant spin-flip nature of excitations is confirmed in both materials.

Abstract

We use Resonant Inelastic X-ray Scattering (RIXS) to compare the doping dependence of magnetic excitations of an Infinite-Layer nickelate to those of a prototypical superconducting cuprate. The polarization analysis of RIXS spectra establishes the dominant spin-flip nature of the mid-infrared peak in both cases. Hole doping leads to opposite behavior of the magnetic energy in the two materials. By fitting the data with an original Hubbard-based model for dynamic susceptibility, we find that t is comparable in the two materials while U is about twice larger in the nickelate. This finding accounts for the smaller magnetic bandwidth of nickelates and for its decrease upon doping.