Spin wave measurements of exchange constant in Ni-Fe alloy films

The ferromagnetic exchange constant has been measured using spin wave resonance in a number of iron-nickel alloys covering the composition range 60% to 90% nickel. The exchange constant varies smoothly from a value of 1.3 (10
^-6
) erg . cm
^-1
at 60% Ni to an extrapolated value of 0.77 (10
^-6
) at 100% Ni. The data are in significant disagreement with the values published by Rusov.