Low-field magnetocaloric effect in antiperovskite Mn3Ga1−xGexC compounds

• The coexistence of normal and inverse magnetocaloric effect in Mn3Ga1−xGexC.
• The magnetic entropy change determined is strongly history-dependent.
• The phase transitions can be adjusted by the substitution of Ge for Ga.

A series of Mn3Ga1−xGexC (x=0, 0.1, 0.2) compounds were prepared by solid state reaction, and their magnetic properties, phase transitions, and magnetocaloric effect were investigated. All samples, after becoming ferromagnetic below Curie temperature Tc, undergo a first-order ferromagnetic–antiferromagnetic transition at Tt at low temperature, giving rise to conventional and inverse magnetocaloric effect. Tt increases while Tc shows a decrease with the increase of Ge content. Isothermal magnetization curves around Tt are strongly history-dependent, which may result in spurious peak in the magnetic field induced entropy change (ΔSMΔSM). The magnetothermal properties near Tt, compared with those near Tc, are of larger ΔSMΔSM, but have larger magnetic hysteresis and smaller refrigerant capacity.