Giant magnetocaloric effect driven by first-order magnetostructural transition in cosubstituted Ni-Mn-Sb Heusler compounds: Predictions from<i>ab initio</i>and Monte Carlo calculations
Sheuly Ghosh, Subhradip Ghosh
Abstract
Using density functional theory and a thermodynamic model [V. Sokolovskiy et al. Phys. Rev. B 86, 134418 (2012)] in this paper we provide an approach to systematically screen compounds of a given Heusler family to predict ones that can yield giant magnetocaloric effect driven by a first-order magnetostructural transition. We apply this approach to two Heusler series ${\mathrm{Ni}}_{2\ensuremath{-}x}{\mathrm{Fe}}_{x}{\mathrm{Mn}}_{1+z\ensuremath{-}y}{\mathrm{Cu}}_{y}{\mathrm{Sb}}_{1\ensuremath{-}z}$ and ${\mathrm{Ni}}_{2\ensuremath{-}x}{\mathrm{Co}}_{x}{\mathrm{Mn}}_{1+z\ensuremath{-}y}{\mathrm{Cu}}_{y}{\mathrm{Sb}}_{1\ensuremath{-}z}$ obtained by cosubstitution at Ni and Mn sites. We predict four new compounds with potentials to achieve the target properties. Our computations of the thermodynamic parameters relevant for magnetocaloric applications show that the improvement in the parameters in the predicted cosubstituted compounds can be as large as four times in comparison to the off-stoichiometric Ni-Mn-Sb and a compound derived by single substitution at the Ni site where magnetocaloric effects have been observed experimentally. This work establishes a protocol to select new compounds that can exhibit large magnetocaloric effects and demonstrate cosubstitution as a route for more flexible tunability to achieve outcomes better than the existing ones.