Influence of magnetostriction on damping constant of NixFe1-x film with various Ni concentrations (x)

We investigated the influence of magnetostriction on the damping constant (a) of 50-nm-thick NixFe1-x polycrystalline films, with x ranging from 0.66 to 0.86. In the experiments, a and the saturation magnetostriction (lambda(s)) were evaluated with high accuracy, which allowed for an interesting finding suggesting a simple relation between a and lambda(s). In the range of positive lambda(s), a slightly increases as x decreases, whereas a increases from 0.009 to 0.012 with increasing x for negative lambda(s) values. a reaches a minimum when lambda(s) is around zero at x=0.78. These results demonstrate that different behaviors of a depend on positive or negative values of lambda(s). Therefore, particular attention should be paid to the change in magnetoelastic properties and the deterioration of magnetic softness when adjusting a of magnetically soft films. (C) 2011 American Institute of Physics. [doi:10.1063/1.3560905]