Mechanical, half-metallic ferro-magnetic and thermoelectric properties double perovskites Li2W(Cl/Br)6 for spintronic and energy devices: DFT-calculations

Electron spin has improved numerous electronic applications, including quantum computing and data storage. The present research used density functional theory (DFT) within the FP-LAPW system implemented in WIEN2k to comprehensively examine the structural, electrical, magnetic, mechanical, and thermoelectric characteristics of halide double perovskites Li2W(Cl/Br)6. The PBE-sol functional along with the Tran-Blaha modified Becke-Johnson (TB-mBJ) potential is used for precise bandgap calculations while the transport behavior is analyzed with the help of BoltzTraP program. Li2W(Cl/Br)6 crystallize in a stable cubic Fm3̅m state, as evidenced by negative formation energies (− 2.98 and − 2.05 eV for Li2WCl6 and Li2WBr6, respectively) and also with the verification of Born stability conditions. The computed Curie values of 426 K (Li2WCl6) and 394 K (Li2WBr6) demonstrate strong ferromagnetism at ambient temperature. Mechanical investigation suggests ductile response, with Pugh’s ratios more than 1.75 and anisotropy factors less than unity. Electronic band analysis reveals half-metallic properties, including full spin polarization at the Fermi level, caused by p-d and s-d orbital hybridizations in W-site octahedra. Ferromagnetic moments are mostly provided by W d-states, which reinforces strong ferromagnetic coupling. The total magnetic moment of 2µB in Li2W(Cl/Br)6 exhibit strong exchange splitting along with half metallic behavior. Thermoelectric examination shows encouraging transport behavior, with higher Seebeck coefficients and power factors at higher temperatures. Li2W(Cl/Br)6 double perovskites have half-metallic and thermoelectric characteristics, making them suitable for spintronic and energy conversion applications.