Enhanced spin thermoelectric response in half-metallic CoTiTe: Material for spintronic and spin-caloritronic...

We systematically investigate the structural, electronic, magnetic, optical, and spin-dependent thermoelectric features of the half-Heusler CoTiTe alloy using first-principles calculations. Structural optimization confirms that the FM-type 2 configuration is the most energetically favorable phase with a negative formation energy of -0.47 eV/atom. Thermodynamic, mechanical, dynamical, and thermal stability are validated through convex hull analysis, elastic constants, phonon dispersion spectra, and AIMD simulations up to 900 K. CoTiTe exhibits high mechanical rigidity combined with ductile behavior. GGA + U calculations confirm half-metallic ferromagnetism (1 μB/f.u.) in accordance with the Slater-Pauling rule, highlighting its potential for spintronic applications. Broadband optical absorption (visible to UV) and high infrared reflectivity demonstrate its potential for spintronics and optoelectronics. Phonon transport is dominated by low-frequency acoustic modes and shows strong temperature-dependent suppression, resulting in low lattice thermal conductivities of 1.76 W/mK at 300 K and 0.587 W/mK at 900 K. Finally, the spin-dependent thermoelectric analysis demonstrates that the spin figure of merit significantly exceeds the charge counterpart, reaching enhanced values at elevated temperatures, thereby positioning CoTiTe as a promising candidate for spin-caloritronics and multifunctional energy applications.