Giant magnetostriction by design: A first-principles screening of Co-based Heusler alloys

The pursuit of high-performance, rare-earth-free magnetostrictive materials is crucial for advancing technologies in sensing, actuation, and microelectromechanical systems. Heusler alloys represent a promising, yet underexplored, class of materials for this purpose. In this work, we perform a systematic first-principles investigation of the magnetostrictive properties of 25 Co-based full Heusler alloys, ${\mathrm{Co}}_{2}\mathrm{YZ}$ (Y = V, Cr, Mn, Fe, Co; Z = Al, Ga, Si, Ge, Sn). Our screening identifies ten compounds with large predicted magnetostriction ($|{\ensuremath{\lambda}}_{001}|>100$ ppm), highlighted by ${\mathrm{Co}}_{3}\mathrm{Si}$ with a giant value of -966 ppm. Furthermore, we demonstrate two effective strategies for engineering magnetostriction: (i) tuning the Fermi level, which enhances the magnetostriction of ${\mathrm{Co}}_{3}\mathrm{Sn}$ to -905 ppm via Sb doping and (ii) amplifying the spin-orbit coupling, which boosts the magnetostriction of ${\mathrm{Co}}_{2}\mathrm{CrGa}$ to a colossal -1008 ppm through Re substitution. Our analysis reveals a general predictive rule, uncovering a linear relationship between the magnetostriction and the choice of the $Y$-site transition metal. This work not only identifies novel candidates for magnetostrictive applications, but also establishes clear, physically grounded design principles to accelerate the discovery of new functional magnetic materials.