Exploring magnetocaloric and heat capacity behavior in Fe doped Mn5Ge3 alloy

Abstract

Magnetocaloric properties of hexagonally structured Mn5−xFexGe3 (x=0.15, 0.3, and 0.5) alloys have been investigated using DC magnetization and heat capacity measurements. The maxima of entropy change, −ΔSmmax∼5.04(5.57) J/kg K, along with an adiabatic temperature change of ΔTadmax∼5.05(7.25) K was observed for x=0.15(0.5) at an applied magnetic field H=5 T. With the scaling analysis of −ΔSm, the rescaled curves collapse onto a single universal curve anticipated by the mean-field theory, revealing a second-order type of magnetic transition. Furthermore, −ΔSmmax follows a power law of Hn with n=0.597(3), 0.591(3), and 0.586(3) for Mn5−xFexGe3 (x=0.15, 0.3, and 0.5) alloys, respectively. The refrigerant capacity (RC) is increased from 400 J/kg (for x=0.15) to 420 J/kg (for x=0.5) with Fe doping in Mn5Ge3. Moreover, the coefficient of refrigerant performance (CRP) enhances with Fe doping from 0.06 (for x=0.15) to 0.1 (for x=0.5). Thus, high RC and reasonable CRP values for earth-abundant Mn-based Mn–Fe–Ge alloys promise the potential to replace the high-cost rare-earth (Gd) and heavy metal-based metallic magnetocaloric systems for use in environment-friendly magnetic refrigeration technology.