Specific heat and magnetocaloric effect of the Mn5Ge3 ferromagnet

The specific heat Cp(T) of the Mn5Ge3 ferromagnet has been studied in a wide temperature range of 2–400 K. The ferromagnetic ordering has been confirmed at TC = 297.4 K, however the behaviour of Cp(T,H) in small magnetic fields suggests a presence of a weak antiparallel component in the magnetic structure. The combination of the Cp(T,H) and magnetization M(T,H) measurements enabled the determination of not only the isothermal magnetic entropy change ΔSM but the adiabatic temperature change ΔTad as well. It has been also found that the mechanical milling process leads only to a moderate drop of the magnetocaloric effect. The reduction of the grain size by 50% decreases the relative cooling power by 28%.