Enhancement of Curie temperature in amorphous CoY alloys

Magnetic properties of amorphous CoY alloys are investigated on the basis of a new theory of amorphous magnetic alloys. It is shown that the enhanced Curie temperatures TC increase linearly from a critical concentration of ferromagnetism towards amorphous pure Co with increasing Co concentration. The enhancement of TC is explained by the magnetic energy gain due to the structural disorder in the region close to amorphous pure Co, while it is dominated by the change in local atomic configuration around 60 at.% Co. The magnetization vs. concentration curve as well as the effective Bohr magneton number vs. concentration curve are also presented. The former is shown to decrease monotonically with increasing Y concentration in agreement with the experimental data, while the latter is predicted to exhibit a minimum around 55 at.% Co because of the occurrence of weak ferromagnetism. © 1994.