Analysis of the magnetic transition and magnetocaloric effect in Mn5Ge2.9Ag0.1 compound

Here we investigate analytical models to understand magnetic and magnetocaloric properties of Mn5Ge2.9Ag0.1 compound prepared by arc-melting method. The Mn5Ge2.9Ag0.1 alloy, undergoing a second-order transition, shows a maximum magnetic entropy change of about 6.86 J/kgK and the relative cooling power (RCP) value of 386 J/kg at 298 K under a field change of 5T. Based on a phenomenological model, the magnetocaloric properties obtained from temperature-dependent magnetization data are in good agreement with the experimental results. To give a better understanding of magnetic transition and the effective magnetic entropy change, we quantify the coupling of lattice energy and electronic energy contribution to the effective magnetic entropy change from a Landau theory plus Bean-Rodbell model. Interestingly, the coupling of lattice energy and electronic energy presents a positive value of up to 4.5% of the effective magnetic entropy change, producing a deleterious impact on the effective magnetic entropy change. The results suggest that the Mn5Ge2.9Ag0.1 system could be a very attractive material for room-temperature magnetic refrigeration applications. (C) 2019 Elsevier B.V. All rights reserved.