Magnetocaloric effect and sign reversal of magnetic entropy change across the spin reorientation temperature in R3Fe5O12 (R = Gd, Dy)

The cubic structure with space group Ia3‾d for Gd3Fe5O12 and Dy3Fe5O12 are successfully synthesized and the magnetic behaviors are studied in details. The dc magnetization measurements show that an obvious negative magnetization phenomenon is observed in Gd3Fe5O12 and the compensation temperature is as high as 287 K. An adjustable magnetic switching effect with good cyclicity can be realized near the compensation temperature. Besides, sign reversal of magnetic entropy change across the spin reorientation temperature has been observed in both of Gd3Fe5O12 and Dy3Fe5O12, which is ascribed to the transition of the ordered collinear structure to the distorted non-collinear structure with lower order as the temperature decreases. Moreover, the magnetocaloric effect at the lower temperatures is also studied and the maximum values of magnetic entropy change are 3.40 J kg−1 K−1 at 40 K and 3.51 J kg−1 K−1 at 58 K for Gd3Fe5O12 and Dy3Fe5O12, respectively.