Magnetic and magneto-thermal properties of ferrimagnetic alloys (Er1−x Y x )(Co0.84Fe0.16)2 and their dependence on the orientations of resultant and sublattice magnetizations

Abstract

In this paper structure, magnetic and magneto-thermal properties: magnetic entropy change (ΔS m) and refrigeration capacity (q) of Er1–x Y x (Co0.84Fe0.16)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.