Computational strain engineering and Hubbard's effect investigation on Li2CuWX6 (X = Cl, Br) double perovskites: A promising Route to spintronic Innovation

Abstract

There are many advantages to spintronics, including higher speeds at lower power consumption, improved robustness, and the potential to ultimately replace conventional electronics. Spintronic devices can benefit greatly from the spin polarization ferromagnetism found in double perovskites (DPs). We used the PBE-sol approximation to figure out the exchange-correlation potential and the mBJ potential and Hubbard U-corrections in order to get a good idea of the electronic band structure (BS) and density of states (DOS). A net effect of spin orbit coupling (SOC) was also kept in consideration for the electronic conduction. Both materials exhibit thermodynamic stability in a cubic structure due to their negative formation energies and no imaginary phonon frequencies or lattice vibrations. We identify ferromagnetic compounds using spin-based energy volume optimization and exchange constant values. It is distinctly observed from 3-d states of tungsten (W) are the primary contributor to the magnetic moment arising from exchange splitting, which in turn causes ferromagnetism. An direct band gap (E_g) was found in both Li₂CuWCl₆ and Li₂CuWBr₆, with Eg values of 2.09 eV and 1.53 eV, respectively. We discovered this by analyzing the electronic density of states and band structure (BS). The optical spectra of materials revealed significant UV absorption. Finally, we examined the thermoelectric (TE) characteristics of compounds in the 200–800 K temperature range via BoltzTrap algorithm. The material's thermal conductivity (κe/τ) and electrical conductivity (σ/τ) were included in the transport parameter, which increased with temperature. On the other hand, the power factor (P.F) and Seebeck coefficient (S) decreased with rising temperature. Moreover, Li₂CuWCl₆ and Li₂CuWBr₆ both had high figures of merit (ZT) of 0.74 and 0.72, respectively. The optimistic results of this study demonstrate the potential of the materials under discussion in the domains of thermoelectric, optoelectronics, and spintronics.