Low magnetic damping of ferrimagnetic GdFeCo alloys

TL;DR

This study measures the Gilbert damping in GdFeCo ferrimagnetic alloys, revealing it remains low and stable across temperature variations, challenging previous theories about divergence at the angular momentum compensation point.

Contribution

It demonstrates that magnetic damping in RE-TM ferrimagnets is governed by electron scattering at the Fermi level rather than total angular momentum.

Findings

Gilbert damping parameter as low as 0.0072

Damping remains nearly constant across temperature range

Contradicts previous predictions of divergence at compensation temperature

Abstract

We investigate the Gilbert damping parameter for rare earth (RE)-transition metal (TM) ferrimagnets over a wide temperature range. Extracted from the field-driven magnetic domain-wall mobility, the Gilbert damping parameter was as low as 0.0072 and was almost constant across the angular momentum compensation temperature, starkly contrasting previous predictions that the Gilbert damping parameter should diverge at the angular momentum compensation temperature due to vanishing total angular momentum. Thus, magnetic damping of RE-TM ferrimagnets is not related to the total angular momentum but is dominated by electron scattering at the Fermi level where the TM has a dominant damping role.