Magnetic properties of amorphous Co-B alloys

Magnetization measurements on amorphous Co-B alloys have been made in the range of B content from 19 at% to 26 at% to obtain the B concentration dependence of the magnetic moment and the spin wave stiffness constant. The magnetic moment μ per Co atom decreases linearly with the increase of the B concentration. The rate of decrease of the magnetic moment is explained by assuming that the outer electron (2S²2p) of metalloid atoms are donated to the d-holes of the transition metals. Information of the exchange stiffness constant D was obtained from the temperature dependence of the magnetization using the spin wave analysis. D vs composition has a linear concentration dependence just like that of μ. From the composition dependence of D and μ, we can estimate the value of D/μ which is a quantity proportional to the average exchange integral and we obtained a result that the D/μ is almost constant against composition.