THEORETICAL-ANALYSIS OF THE SPIN-DENSITY DISTRIBUTIONS IN Y2FE17N3 AND Y2FE17C3

The electronic structures and spin-density distributions in Y 2Fe17N3 and Y2Fe17C 3 are calculated using the self-consistent spin-polarized orthogonalized-linear-combination-of-atomic-orbitals method. The N or C atoms are assumed to occupy the (9e) sites in the rhombohedral structure. The Fe (18f) and N or C at the (9e) site form covalent bonds which result in a very nonspherically symmetric spin-density distribution. The calculation shows a reduced moment for the Fe (18f) sites due to doping. However, the moments at other sites are increased due to lattice expansion. There are some differences in the spin-density distribution between N and C at the (9e) site. By comparing with the results of calculation on the pure Y2Fe17 at different volumes, changes in moment enhancement and density of states at the Fermi level due to lattice expansion alone and that due to the chemical effect of introducing N or C are separated.