The effects of Tb doping on the negative and positive magnetocaloric effects of Mn3Ga1−xTbxC (0.02 ≤ x ≤ 0.05)

Abstract

Generally, researchers focus on the great negative magnetocaloric effect (NMCE) rather than the positive magnetocaloric effect (PMCE) in Mn3GaC. Here, we prepared Mn3Ga1−xTbxC composites with a partial substitution of Ga by Tb. Tb doping expands the canted-ferromagnetic phase (CFM) between the anti-ferromagnetic and ferromagnetic phase in Mn3Ga0.97Tb0.03C. The CFM phase can be as a boundary to separate the NMCE from PMCE. It is possible to combine the NMCE and PMCE for refrigeration. Compared with NMCE in Mn3GaC, NMCE–PMCE combination in Mn3Ga0.97Tb0.03C displays a much larger operating temperature range without loss of magnetic entropy changes. Therefore, the NMCE–PMCE combination is valuable for improving the operating temperature range of magnetocaloric effect materials. It also provides a new idea for refrigeration applications.