Influence of nickel substitution in an Fe-Sb triangular antiferromagnetic system

Abstract

The iron-antimony system, which occurs in a Ni-As structure, shows interesting magnetic properties and has been investigated by several workers. In order to explore these properties further, we have studied (Fe_1-yNi_y)_1+xSb by x-ray diffraction and Mossbauer methods in the concentration ranges 0.02≤y≤0.42 and 0.08≤x≤0.16. Through analysis of the x-ray data, it has been found that these samples are isotypic with Fe_1+xSb, wherein Fe is substituted by Ni, and that the American Society for Testing and Materials data file for Fe_1+xSb needs modification. Using Mossbauer spectroscopic measurements in a transmission geometry at different temperatures, we have determined the Neel temperatures, which decrease linearly with increasing y. The substitution of Ni atoms in the Fe-Sb lattice produces two new magnetic hyperfine fields which are about 40% and 80% lower than the original field in Fe-Sb. The magnitude of these fields is independent of Ni concentration, whereas the density of sites with these fields increases monotonically with the increase in y.