MAGNETIC ENTROPY IN NANOCOMPOSITE BINARY GADOLINIUM ALLOYS

Investigation on magnetocaloric effects, magnetic entropy, Curie tempe rature, and specific heat of nanocomposite binary gadolinium alloys Gd -Tb, Gd-Zn, and Gd-Y has been carried out with an applied magnetic fie ld of 1 T and in a temperature range of 233-313 K. Compared with the r espective bulk alloys, the as-prepared nanocomposite alloys were found to have higher specific heat and lower Curie temperature. The nanocom posite Gd-Y alloy exhibited distinctive enhancement of both magnetocal oric effect and magnetic entropy over that of the bulk alloy. The find ing is of importance for developing new materials for magnetic refrige ration at room temperature. A discussion concerning the enhanced magne tic entropy in nanometer superparamagnetic systems is presented in det ail. (C) 1996 American Institute of Physics.