Magnetic properties and magnetocaloric effects in amorphous and crystalline GdCuAl ribbons

The magnetic properties and magnetocaloric effects of amorphous and crystalline GdCuAl ribbons have been experimentally studied. The amorphous ribbon exhibits a superparamagnetic behaviour, as demonstrated by the appearance of a maximum in the in-phase linear susceptibility chi(1)' and a minimum in the in-phase nonlinear susceptibility chi(3)' at similar to 25 K. In the high temperature range, chi(1)' and chi(3)' vary following the Curie-Weiss law and the 1/T-3-law, respectively. For crystalline GdCuAl; ribbons, a ferromagnetic-to-paramagnetic second-order phase transition takes place around 81 K. The maximum magnetic entropy change and refrigerant capacity are as high as similar to 10.1 J kg(-1) K-1 and 460 J kg(-1), respectively, for a field change of 0-5 T. These features make crystalline GdCuAl an attractive candidate for a low-temperature magnetic refrigerant. (C) 2008 Elsevier Ltd. All rights reserved.