Field dependence of magnetic entropy change in Mn5Ge3 near room temperature

Abstract

We present the investigation of the magnetic field dependence of magneto-caloric properties in Mn5Ge3 with a near-room temperature second order phase transition (SOPT) at Tc ≃ 297.5 K. The isothermal entropy change (∣ΔSM∣) exhibits a high-field (H ≥ 3 T) power-law behavior with exponent value of 0.58 (near TC), in corroboration with critical exponents study. The maximum entropy change (∣ΔSM∣max∣) exhibits a H2∕3 dependence with addition of spatial inhomogeneity and higher order magnetization (up to M6) terms in Landau′s theory of SOPT. The nearly identical magnetic field evolution of magnetocaloric effect and a reasonably high refrigerant capacity of 398 J/kg (at 5 T) for inexpensive and abundant Mn5Ge3 make it a promising alternative to rare-earth Gadolinium for near-room temperature magnetic refrigeration technology.