Field dependence of magnetic entropy change in Mn5Ge3 near room temperature

• Published in: Journal of alloys and compounds 2021-09, Vol.876, p.159908, Article 159908
• Main Authors: Lalita, Rathi, A., Pardeep, Verma, Ajay Kumar, Gahtori, B., Gautam, Arvind, Pant, R.P., Babu, P.D., Basheed, G.A.
• Format: Article
• Language: English
• Subjects: Critical exponents; Entropy; Gadolinium; Germanides; Inhomogeneity; Magnetic entropy change; Magnetic fields; Magnetic properties; Magnetism; Magnetocaloric effect; Manganese compounds; Maximum entropy; Phase transitions; Rare earth elements; Room temperature
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2021.159908

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. •Ferromagnetic ordering at TC = 297.5 K is governed by 3D Ising spin interactions in Mn5Ge3.•Isothermal entropy change exhibits a high-field (H ≥ 3T) power-law behaviour, in ratification to critical exponent study.•Maximum isothermal entropy change follows Landau′s theory of SOPT with inclusion of spatial magnetic inhomogeneity effect.