CPA theory of the magnetization in rare earth transition metal alloys

Calculations were made of the magnetic moment per atom of the transition metal and the rare earth metal in the intermetallic compounds, Gd1-xNix, Gd1-xFex, Gd1-xCox, and Y1-xCox. A simple model of the disordered alloy consisting of spins localized on the rare earth atoms and interacting with a narrow d-band is considered.

The magnetic moment of the alloy at zero temperature is calculated within the molecular field and Hartree-Fock approximations. Disorder is treated in the coherent potential approximation. Results are in good agreement with the experimental data obtained for the crystalline and amorphous intermetallic compounds.

It is shown that the temperature dependence of the magnetic moments and Curie and ferrimagnetic compensation temperatures can be accounted for by a simple model assuming a RKKY interaction between the rare-earth moments and the transition metal pseudo spin. The interaction is mediated by an effective alloy medium calculated using the CPA theory and elliptic densities of states.