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

Abstract

We use ferromagnetic resonance measurements to study the compositional dependence of the Gilbert damping constant α for Fe100-xRhx thin films. We find that α decreases upon increasing the Rh composition up to x = 20, whereas it increases for 20 < x < 27. The minimum value of α around x = 20 is as low as (9 ± 1) × 10 - 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 α at a higher Rh composition likely arises from the evolution of possible antiferromagnetic correlation. The results demonstrate that Fe100-xRhx is a promising low-damping material for spintronic applications.