Influence of magnetostriction on damping constant of Ni_xFe _1-x film with various Ni concentrations (x)

We investigated the influence of magnetostriction on the damping constant (α) of 50-nm-thick Ni_xFe_1-x polycrystalline films, with x ranging from 0.66 to 0.86. In the experiments, α and the saturation magnetostriction (λ_s) were evaluated with high accuracy, which allowed for an interesting finding suggesting a simple relation between and _λs. In the range of positive _λs, α slightly increases as x decreases, whereas increases from 0.009 to 0.012 with increasing x for negative _λs values. reaches a minimum when _λs is around zero at x=0.78. These results demonstrate that different behaviors of depend on positive or negative values of _λs. Therefore, particular attention should be paid to the change in magnetoelastic properties and the deterioration of magnetic softness when adjusting of magnetically soft films.