Reverse magnetostructural transformation and adiabatic temperature change in Co- and In-substituted Ni-Mn-Ga alloys

Abstract

A careful characterization of the magnetocaloric effect in Co-substituted Ni-Mn-Ga Heusler alloys, based both on direct and indirect methods, is presented. In the present paper, adiabatic temperature change values ($\ensuremath{\Delta}{T}_{\mathrm{ad}}$) up to 1.6 K in 1.9 T were measured across the magnetostructural transformations. The studied samples, with similar transformation temperatures and comparable entropy changes, show surprising differences of the $\ensuremath{\Delta}{T}_{\mathrm{ad}}$. In order to gain better insight into the behavior of the $\ensuremath{\Delta}{T}_{\mathrm{ad}}$ peak values among different samples, a qualitative model is proposed based on magnetization and magnetothermal data.