Tuning magnetic exchange interactions to enhance magnetocaloric effect in Ni50Mn34In16 Heusler alloy: Monte Carlo and ab initio studies

• A decrease of exchange couplings in Ni50Mn34In16 leads to increase values of the MCE.
• A switch off FM Mn--Mn interaction in the martensite gives a rise of the inverse MCE.
• A switch off AF Mn--Mn interactions results to decrease of the inverse MCE.
• A reduction of exchange couplings can be realized by a doping with nonmagnetic atoms.

Influence of the strength of magnetic exchange interactions and impact of a ferromagnetic-antiferromagnetic exchange competition on magnetocaloric effect in a Ni50Mn34In16 Heusler alloy are studied by a Monte Carlo simulation. Temperature dependencies of magnetic and magnetocaloric properties are obtained in the framework of Potts and Blume-Emery-Griffiths models. It is shown that a decrease of the exchange interactions as well as “switching off” ferromagnetic interactions between the Mn atoms in the martensite favors the inverse magnetocaloric effect in Ni50Mn34In16. Contrary, “switching off” antiferromagnetic interactions depletes the inverse magnetocaloric effect. It is supposed that the exchange interactions in Ni–Mn-In alloys can be tuned favorably by a doping of the host alloys with nonmagnetic or antiferromagnetic atoms, e.g., B, Cu, Cr, etc.