Correlation between deformation and total entropy change at the first-order magnetic transition of Fe2P-based magnetocaloric materials

While there is a growing consensus that lattice is an important source of entropy change at structural or elastic first-order magnetic transitions (FOMT) with finite volume change, the case of volume preserving transitions (ΔV = 0) remains more controversial. Here, the evolution of the total transition entropy change within the Fe2P family is presented as a function of the discontinuity on the ratio of the cell parameters. A striking correlation between ΔStr and Δ(c/a) is observed. This relationship is a first step towards a systematization of the FOMT properties in the Fe2P materials system. It also demonstrates that deformation can play a leading role in volume preserving FOMT.