Magnetocaloric effect in bulk amorphous Pd40Ni22.5Fe17.5P20 alloy

We have studied the temperature (T) and field (H) dependence of the magnetocaloric effect in a bulk amorphous Pd40Ni22.5Fe17.5P20 alloy. With decreasing T, and depending on H, the alloy exhibits superparamagnetic, field-induced ferromagnetic, and spin-glass behavior. The temperature-dependence of the magnetic entropy change, DeltaS=S(H)-S(H=0), exhibits extreme values: a minimum at the superparamagnetic-to-ferromagnetic transition and a maximum at the ferromagnetic-to-spin-glass transition. At 80 K, and for H=50 kOe, the entropy change is -0.029 k(B) per Fe atom in the alloy. This value compares favorably with that measured in other crystalline and amorphous Fe-based alloys, but it is lower than that measured in some rare-earth elements. (C) 2002 American Institute of Physics.