AB-INITIO CALCULATIONS OF THE CURIE-TEMPERATURE OF COMPLEX PERMANENT-MAGNET MATERIALS

The nitrogenation of rare-earth-transition-metal compounds (R2M17) mor e than doubles the Curie temperature (T-c) of iron-rich compounds but lowers T-c of cobalt-rich compounds. Self-consistent spin-polarized el ectronic-structure calculations are carried out to understand this unu sual behavior of T-c. T-c is calculated using the Heisenberg model and finite-size scaling in Monte Carlo simulations. The calculated values of T-c are in very good agreement with the experimental data.