Compositional dependence of Gilbert damping constant of epitaxial Fe100-xRhx thin films

We use ferromagnetic resonance measurements to study the compositional dependence of the Gilbert damping constant alpha for Fe100-xRhx thin films. We find that alpha decreases upon increasing the Rh composition up to x = 20, whereas it increases for 20<27. The minimum value of alpha around x = 20 is as low as (9 +/- 1)x10-4, which is comparable to that of Fe75Co25 alloys-the lowest damping material among metallic ferromagnets. Considering the compositional dependence of the density of states at the Fermi level, we attribute the low damping to the decrease in the density of states at x = 20. An enhancement in alpha at a higher Rh composition likely arises from the evolution of possible antiferromagnetic correlation. The results demonstrate that Fe100- Rh-x(x) is a promising low-damping material for spintronic applications. Published under license by AIP Publishing.