Experimental evidences of enhanced magnetocaloric properties at room temperature and half-metallicity on Fe2MnSi-based Heusler alloys

Abstract Heusler alloys are widely studied due to their interesting structural and magnetic properties, like magnetic shape memory ability, coupled magneto-structural phase transitions and half-metallicity; ruled, for many cases, by the valence electrons number ( N v ). The present work focuses on the magnetocaloric potentials of half-metals, exploring the effect of N v on the magnetic entropy change, preserving half-metallicity. The test bench is the Si-rich side of the half-metallic series Fe 2 MnSi 1 − x Ga x . From the obtained experimental results it was possible to propose | Δ S | m a x = Δ H 0.8 ( α + β N v ) , i.e., the maximum magnetic entropy change depends in a linear fashion on N v , weighted by a power law on the magnetic field change Δ H ( α and β are constants experimentally determined). This phenomenological model opens doors for further theoretical investigations. In addition, it was also possible to predict a new multifunctional Heusler alloy, with enhanced magnetocaloric effect, Curie temperature close to 300 K and half-metallicity.