57Fe Mössbauer Effect Study of Y(Fe1 – xNix)2 Synthesized under High Pressure

The measurements of magnetic hyperfine fields (MHF), Hhf, and isomer shift, δ, in Y(Fe1 – xNix)2 intermetallic compounds (the MgCu2 structure type) synthesized at high pressure are performed. The MHF values that appear on 57Fe nuclei at a nickel concentration x below 20 at % practically do not change and are approximately equal to 22 T, and in the range from x = 0.4 to 0.98 they decrease linearly with an increase in the Ni concentration. However, linear extrapolation of the hyperfine field as a function of Ni concentration does not lead to its disappearance in YNi2. For YFe2, the rotation of the easy axis from the [101] direction to the [111] direction with increasing temperature is found. As the Ni concentration increases to x = 0.3 at a temperature of 5 K, the easy magnetization axis [101] is observed, and at x = 0.4 the axis changes direction to [100]. Based on the shape of the concentration dependence of the hyperfine field, it is assumed that during the crystallization of Y(Fe1 – xNix)2 under high pressure conditions, a magnetic moment exists on Ni ions. First-principles calculations of magnetic properties and hyperfine interactions are performed, which are consistent with experiment.