Effect of doping elements on the damping constant of (Ni-Fe _{1- x}M _x (M=Ga, Ag, Mo, and W) films

This paper describes the relationship between the damping constant α and saturation magnetostriction λ _s of (Ni-Fe1-xM _x (M=Ga, Ag, Mo, and W; 0\,<!xleq \,0.10) films to clarify the effect of doping elements on α and other magnetic properties in these films. For M=Ga and Ag, the change of α with x is closely related with that of λ _s, while it is not consistent with that of λ _s when M= Mo and W. These results suggest that both α and λ _s are correlated with each other as the single fcc Ni-Fe phase remains unchanged with x for M=Ag and Ga, while that α and λ _s are independent from each other because of coexistence of fcc Ni-Fe and new phases when M=Mo and W. Therefore, it is pointed out that α can be controlled effectively by selecting the doping elements which do not induce a new phase in the Ni-Fe binary alloy, but one should be careful about a change in magnetoelastic properties which may deteriorate magnetic softness. These results for M=Ga and Ag also suggests that (Ni-Fe1-xM _x films are good examples to give evidence that the magnetoelastic energy E _\sigma has the same intrinsic origin with α.