Magnetocaloric properties at the austenitic Curie transition in Cu and Fe substituted Ni-Mn-In Heusler compounds

We present a study on the Curie transition of austenitic Ni-Mn-In full Heusler compounds when Mn atoms are replaced by Fe or Cu. The substituted compounds are designed to present a relevant magnetocaloric effect at the second order Curie transition of the austenitic phase near room temperature. We show that Fe and Cu modify the magnetic moments and interactions responsible of the localized magnetism in the L21 ordered cubic structure, resulting in a change of the Curie temperature and saturation magnetization of the compound. Neutron diffraction experiments and electron microscopy analysis were used to study the sites occupancy of doping atoms and the presence of secondary phases, thus possibly optimizing the annealing protocols to obtain homogeneous samples even at high Cu/Fe concentrations. On this basis, a series of quinary compounds with a tunable Curie temperature and high values of saturation magnetization (100-110 Am2/kg at 80 K) was successfully synthesized. The obtained results show the feasible fine tuning of the Curie temperature at which the peak of the magnetocaloric effect is realized, highlighting a new promising strategy to design graded regenerators for room temperature magnetocaloric applications. 0 2021 Elsevier B.V. All rights reserved.

Automated summary

This study investigates the Curie transition of austenitic Ni-Mn-In full Heusler compounds by replacing Mn atoms with Fe or Cu. It is found that Fe and Cu modify the magnetic moments and interactions, resulting in changes in the Curie temperature and saturation magnetization of the compound. The study successfully synthesizes quinary compounds with tunable Curie temperature and high saturation magnetization, highlighting a promising strategy for designing regenerators for room temperature magnetocaloric applications.