(Ru1−xCo _<i>x</i> ) ₂ FeSi Heusler alloys: Bridging spintronic, energy harvesting and high-strength structural applications

Heusler alloys constitute a versatile class of materials with highly tunable structural, electronic, magnetic and optical properties, making them key candidates for next-generation technologies in spintronics, energy conversion, photonics and advanced functional applications. In particular, (Ru[Formula: see text]Co x ) 2 FeSi Heusler alloys demonstrated multifunctional potential, showing promise for spintronic, magnetic, thermodynamic, optoelectronic and structural applications. First-principles calculations revealed that Ru-rich alloys ([Formula: see text], 0.25) crystallized in the disordered B2 phase with metallic character and higher stiffness, whereas Co-rich alloys ([Formula: see text], 0.75 and 1) stabilized in the ordered L2 1 phase, exhibiting half-metallic ferromagnetism, enhanced ductility and magnetic moments increasing up to [Formula: see text]B. Optical analysis demonstrated strong interband transitions, pronounced refractive index peaks and tunable reflectivity across the infrared–ultraviolet range, confirming suitability for infrared shielding, photovoltaic coatings and optical sensing. These findings established (Ru[Formula: see text]Co x ) 2 FeSi alloys as adaptable candidates for next-generation multifunctional devices.