Magnetic Excitations in Strained Infinite-layer Nickelate PrNiO2

TL;DR

This study investigates magnetic excitations in strained PrNiO2 thin films to understand their role in superconductivity, revealing that strain-induced Tc enhancement is likely not mediated by spin excitations.

Contribution

It provides experimental evidence that magnetic excitations are not significantly affected by strain in PrNiO2, challenging the idea that spin fluctuations drive superconductivity in nickelates.

Findings

Magnon bandwidth shows minimal response to strain.

Superconducting Tc increases dramatically with strain.

Magnetic excitations are unlikely to mediate pairing in PrNiO2.

Abstract

Strongly correlated materials often respond sensitively to the external perturbations. In the recently discovered superconducting infinite-layer nickelates, the superconducting transition temperature can be dramatically enhanced via only ~1% compressive strain-tuning enabled by substrate design. However, the root of such enhancement remains elusive. While the superconducting pairing mechanism is still not settled, magnetic Cooper pairing - similar to the cuprates has been proposed. Using resonant inelastic x-ray scattering, we investigate the magnetic excitations in infinite-layer PrNiO2 thin films for different strain conditions. The magnon bandwidth of PrNiO2 shows only marginal response to strain-tuning, in sharp contrast to the striking enhancement of the superconducting transition temperature Tc in the doped superconducting samples. These results suggest the enhancement of Tc is not mediated by spin excitations and thus provide important empirics for the understanding of superconductivity in infinite-layer nickelates.