Recent Progress of Magnetic Refrigerant Materials at High Temperatures

Recently, much attention has been given to magnetic refrigeration, because of its energy efficiency and environmental safety. The concept of magnetic refrigeration is based on the magnetocaloric effect (MCE); therefore the development of magnetic materials with a large MCE is strongly desired. In this article we first review the recent development of magnetic refrigerator at temperatures of 20-300K. We then report on the recent progress of magnetic materials with a large MCE. The giant MCE was observed in Er (Co1-xNix)2, MnAs1-xSbx and Mn3GaC in temperature ranges of below 30K, above 220K and at around 160K, respectively. The origin of the giant MCE in these compounds is the first-order magnetic transition (FOMT). The advantage of utilizing the FOMT system as a magnetic refrigerant material is also described.