Yttrium influence on magnetic properties and hyperfine interactions in multicomponent substitution alloys (Dy$_{1-x}$Y$_x$)$_{0.8}$Sm$_{0.2}$Fe$_2$

The paper presents the results of investigation of structure, magnetic properties and superfine interactions in multicomponent alloys based on rare-earth elements $(R)$, Sm and their analogue Y of $R$Fe$_2$ stoichiometry. To obtain new multicomponent alloys, a complex type of substitution in the rare-earth sublattice was used, namely, weakly magnetic samarium atoms at a fixed concentration of 20 at.% were first introduced into the dysprosium sublattice, followed by non-magnetic yttrium atoms at the values of the substitution parameter $x$ = 0, 0.2, 0.4, 0.6, 0.8, 1.0. This type of substitution, first of all, leads to the competition of exchange interactions between magnetically active ions in a wide temperature region of their magnetic ordering. The competition also leads to a number of unique magnetic phase transformations in the resulting alloys, including the phenomenon of magnetic compensation of the rare-earth and 3d sublattice, as well as spin reorientation. The values of the main parameters of Mossbauer spectra on $^{57}$Fe nuclei in (Dy$_{1-x}$Y$_x$)$_{0.8}$Sm$_{0.2}$Fe$_2$alloys and their dependence on yttrium concentration at $T$ = 300 K have been determined. The field dependences of magnetostriction in fields up to 12 kOe have been investigated.