Band theoretical investigation of the Curie temperatures of modified R(2)Fe(17)-based intermetallic compounds

The Curie temperatures of several Nd2Fe17-based intermetallic compounds are calculated based on the spin-fluctuation model of Mohn and Wohlfarth and the band structure results calculated using the self-consistent orthogonalized linear combinations of the atomic orbitals method in the local spin density approximation. It is shown that the calculated T-c can qualitatively account for the observed T-c enhancement in this class of modified compounds by interstitial doping of N or C, or by elemental substitution of Fe by Si, Al or Ga. A simple explanation of T-c enhancement based purely on the magnetovolume effect is not justified. It is also shown that neither the Stoner-Curie temperature nor the characteristic spin-fluctuation temperature is adequate to explain the experimentally observed T-c enhancement in these compounds. (C) 1996 American Institute of Physics.