Magnetic properties of Gd_xY_1−xFe₂Zn₂₀: Dilute, large-S moments in a nearly ferromagnetic Fermi liquid

Single crystals of the dilute, rare earth bearing, pseudoternary series Gd_xY_1−xFe₂Zn₂₀ were grown out of Zn-rich solution. Measurements of magnetization, resistivity, and heat capacity on Gd_xY_1−xFe₂Zn₂₀ samples reveal ferromagnetic order of the Gd³⁺ local moments across virtually the whole series (x⩾0.02). The magnetic properties of this series, including the ferromagnetic ordering, the reduced saturated moments at base temperature, the deviation of the susceptibilities from Curie-Weiss law, and the anomalies in the resistivity, are understood within the framework of dilute, S moments (Gd³⁺) embedded in a nearly ferromagnetic Fermi liquid (YFe₂Zn₂₀). The s-d model is employed to further explain the variation of T_C with x as well as the temperature dependences of the susceptibilities.