X-ray diffraction, magnetization and nuclear magnetic resonance study of Y2Fe17-xGax

A combined x-ray diffraction, magnetization and nuclear magnetic resonance ( and ) study of the system is presented. It is found that the substitution of larger Ga atoms for Fe causes a transformation from the hexagonal to rhombohedral structure and an overall average lattice expansion of per formula unit per Ga atom. Measurements on magnetically aligned powders yielded values for the anisotropy field and the average moment per Fe atom. Consistent with a change from planar to uniaxial anisotropy, the anisotropy field decreases with increasing Ga content and extrapolates to zero for . The average moment per Fe atom as well as the hyperfine field also decrease with Ga content. Using a calculated value of for the Y moment, values for the hyperfine coupling constants of and were obtained for the on-site and transferred contributions, respectively. The experimental results are discussed in terms of a model for the substitution of Ga for Fe in this system, and its relationship to the enhanced Curie temperature.