ELECTRONIC-STRUCTURE AND MAGNETIC-PROPERTIES OF R2FE17NX

The recent discovery of a remarkable improvement in the magnetic properties of nitrogenated R2Fe17 compounds has been a source of considerable excitement in the field of hard magnets. This paper reviews the study of magnetism in these compounds based on self-consistent, spin-polarized electronic-structure calculations. These studies have been carried out on Y2Fe17 compound, a prototype R2Fe17 system. The first calculation for rhombohedral Y2Fe17 was carried out by Coehoorn, who found saturation magnetization in very good agreement with the experimental data. Beuerle, Braun and Fahnle studied hexagonal Y2Fe17 as well as its expanded form due to nitrogenation but without nitrogen atoms. Jaswal, Yelon, Hadjipanayis, Zang and Sellmyer carried out the spin-polarized calculations for hexagonal Y2Fe17 and Y2Fe17N3. Their magnetization results before and after nitrogenation are in very good agreement with the experimental data. Based on the spin-fluctuation theory of Mohn and Wohlfarth their band-structure results correctly predict more than doubling of the Curie temperature upon nitrogenation as observed experimentally.