Magnetocaloric Effect and Critical Behavior in Amorphous Ribbons Gd54Ho6Co25Al14Si

Magnetocaloric effect and critical behavior of amorphous ribbons Gd
₅₄
Ho
₆
Co
₂₅
Al
₁₄
Si were investigated in this paper. Samples were fabricated by a single-roller melt-spinning method at a spinning rate of 20 and 60 m/s. The Curie temperature is 120 K for both samples. A broader phase transition temperature range, however, was found for the sample fabricated at 60 m/s. It was attributed to its higher local disordered structure due to its faster quenching speed. The peak of the magnetic entropy change ΔS
_M
^PK
is 11.01 J · kg
^-1
· K
^-1
and its full-width of the half-maximum is ~90 K at a field change of 0-5 T, which results in a large refrigerant capacity (~990 J · kg
^-1
). The critical behavior around the phase transition temperature was analyzed based on the Arrott plots, and the critical values β, γ, and n were obtained with the conventional Arrott-plot procedure. The values of β and y are very close to those predicated by the mean-field model. The n value, however, obtained from the ΔS
_M
^PK
∝ H
ⁿ
curve is higher than the mean field predicted one, which may be attributed to its amorphous structure.