Negligible thermal contributions to the spin pumping signal in ferromagnetic metal-Platinum bilayers

TL;DR

This study demonstrates that thermal effects do not significantly contribute to spin pumping signals in ferromagnetic metal-Platinum bilayers, clarifying the interpretation of spin pumping experiments.

Contribution

The paper introduces a combined bolometry and ferromagnetic resonance method to evaluate thermal contributions in spin pumping signals, showing their negligible impact in specific bilayer systems.

Findings

Thermal effects are negligible in the studied spin pumping signals.

No measurable spin Seebeck or anomalous Nernst effects were observed.

The proposed method effectively distinguishes thermal from coherent spin signals.

Abstract

Spin pumping by ferromagnetic resonance is one of the most common technique to determine spin hall angles, Edelstein lengths or spin diffusion lengths of a large variety of materials. In recent years, rising concerns have appeared regarding the interpretation of these experiments, underlining that the signal could arise purely from thermoelectric effects, rather than from coherent spin pumping. Here, we propose a method to evaluate the presence or absence of thermal effects in spin pumping signals, by combining bolometry and spin pumping by ferromagnetic resonance measurements, and comparing their timescale. Using a cavity to perform the experiments on Pt\Permalloy and La0.7Sr0.3MnO3\Pt samples, we conclude on the absence of any measurable thermoelectric contribution such as the spin Seebeck and anomalous Nernst effects at resonance