Competition of single-ion anisotropy of Sm and Dy ions during the spin-reorientation transition in Nd$_{1-x-y}$Sm$_{x}$Dy$_{y}$)(FeCo)B supermagnets

It has been found that an increase in the Sm concentration in the range $x$ = 0.05–0.18 in Nd$_{1-x-y}$Sm$_{x}$Dy$_{y}$)(FeCo)B supermagnets leads to a shift in the spin-reorientation transition temperature to higher values, whereas a Dy addition results in a decrease in the transition temperature. Single-ion anisotropy of Sm and Dy ions has different symmetry, making contributions of opposite signs to the resulting magnetic anisotropy of the lattice. Therefore, the threshold temperature $T_S$ of the spin-reorientation transition, which is determined by the balance of magnetic anisotropies of sublattices, can be controlled using ions with different symmetries.