Magnetic excitations in infinite-layer nickelates

TL;DR

This study investigates magnetic excitations in infinite-layer nickelates using RIXS, revealing dispersive modes similar to antiferromagnetic spin waves and emphasizing the importance of Mottness and electron coupling in these materials.

Contribution

First direct measurement of magnetic excitations in infinite-layer nickelates, providing insights into their microscopic physics and similarities to cuprate superconductors.

Findings

Dispersive magnetic excitations with ~200 meV bandwidth in NdNiO2

Lack of long-range magnetic order despite strong spin correlations

Damping of modes increases with doping, indicating coupling to itinerant electrons

Abstract

The discovery of superconductivity in infinite-layer nickelates brings us tantalizingly close to a new material class that mirrors the cuprate superconductors. Here, we report on magnetic excitations in these nickelates, measured using resonant inelastic x-ray scattering (RIXS) at the Ni L3-edge, to shed light on the material complexity and microscopic physics. Undoped NdNiO2 possesses a branch of dispersive excitations with a bandwidth of approximately 200 meV, reminiscent of strongly-coupled, antiferromagnetically aligned spins on a square lattice, despite a lack of evidence for long range magnetic order. The significant damping of these modes indicates the importance of coupling to rare-earth itinerant electrons. Upon doping, the spectral weight and energy decrease slightly, while the modes become overdamped. Our results highlight the role of Mottness in infinite-layer nickelates.