Effect of Ge-site doping on the Ising critical behavior and hysteretic losses of Mn5Ge3

Abstract

The critical behavior and magnetocaloric properties with a room-temperature second-order phase transition of the Mn5Ge3-xAgx (x = 0, 0.1, 0.5, and 1) compounds under the increasing field and decreasing field were studied in detail. The Curie temperature shifts from 299.8 K to 291.5 K with increasing Ag doping content, and the second-order nature has been proved by several tools. Moreover, x = 0 gives the maximum magnetic entropy change near the room temperature, and the corresponding values for both the demagnetization and the magnetization are 7.25 J/kg K and 7.31 J/kg K with a negligible hysteretic loss of 0.447 J/kg at an applied field change of 5 T. The critical exponents have been estimated by various techniques to clarify the magnetic exchange interaction, which is not accordant with a single universality class, and the range of interaction reveals a 3D Ising spin interactions in this series. These results suggest that the present system seems an effective magnetic refrigerant for application in room-temperature magnetic refrigeration.