Magnetocaloric effect of Mn5+xGe3−x alloys

Magnetic properties and magnetocaloric effect (MCE) of off-stoichiometric Mn5+xGe3−x (x = −0.1 and 0.3) were studied. Depletion of Mn (x = −0.1) decreased the magnetic moment of the compound due to the reduction of the ferromagnetic Mn-Mn interactions. Mn5.1Ge2.9 appeared to be near the optimal composition since Mn5.1Ge2.9 exhibited increase in the magnetic moment compared to the stoichiometric compound and further Mn-enrichment beyond x = 0.1 led to the formation of the weakly magnetic secondary phase. Mn5.1Ge2.9 produced the maximum entropy change of 2.9 J kg−1 K−1 at 296 K and the refrigeration capacity of 44.5 J kg−1 with an applied field of 10 kOe, making Mn5.1Ge2.9 a possible candidate magnetic refrigerant with reasonably high magnetic entropy change and negligible hysteresis.