Magnetic and magneto-thermal properties of ferrimagnetic alloys (Er_1−xY_x)(Co_0.84Fe_0.16)₂ and their dependence on the orientations of resultant and sublattice magnetizations

In this paper structure, magnetic and magneto-thermal properties: magnetic entropy change (ΔS _m) and refrigeration capacity (q) of Er_1–xY_x(Co_0.84Fe_0.16)₂ alloys (x = 0, 0.2, 0.4, 0.6, 0.8, 1) in magnetic fields up to 90 kOe in a temperature range of 5–360 K are investigated. An analysis of temperature dependences of magnetization (σ) and high-field susceptibility (χ _hf) showed that in these compounds, three different ferri- and a one ferromagnetic structures are consequently realized. Concentration dependences of magnetic moment at 5 K (μ _f.u.), Curie temperature (T _C), residual magnetization (σ _r) and coercivity (H _c) have been shown to have an extreme at intermediate Y concentration. The character of temperature dependence of magnetic entropy change (ΔS _m(T)) depends on the composition and originates from the type of magnetic structure of the compound and the mutual orientation of R- and 3d- element sublattices magnetization with respect to the resulting one. In compounds with x = 0.6 and x = 0.8 temperature regions with different signs of ΔS _m are observed, reflecting the change of dominating R- or 3d- sublattice in the resulting magnetization. (paper)