Damping Constants of Ni-Fe and Ni-Co Alloy Thin Films

Gilbert's damping constants,
$alpha$
, of Ni-Fe and Ni-Co thin films are determined by Q-band ferromagnetic resonance (FMR) analysis.
$alpha$
is calculated from the resonance width of the FMR spectrum.
$alpha$
of Ni
$_85$
Fe
$_15$
film is found to be 0.0034, which is one-fourth of those of Ni film
$(alpha =0.013)$
and Co
$(alpha =0.013)$
.
$alpha$
of the Ni
$_100 - x$
Co
$_ x$
specimens increases with decreasing the Co concentration from 100 to 68 at%, and the
$alpha$
value of Ni
$_32$
Co
$_68$
film has the maximum value of 0.0021. The
$alpha$
values of the Ni-Co specimens are nearly the same as those of the Co-Cr-Ta and the Co-Cr-Pt.