Theoretical investigation of Sr2TmWO6 (Tm=Cr, Fe, and Co): Analyzing structural, mechanical, optoelectronic and thermoelectric properties for enhanced spintronic and thermoelectric applications

Abstract

This study explores the structural, elastic, dynamic, electronic, magnetic, thermal, and optical properties of Sr₂TmWO₆ double perovskites (Tm = Cr, Fe, Co) using Density Functional Theory (DFT) and the Full-Potential Linearized Augmented Plane Wave (FP-LAPW) method. We applied the Generalized Gradient Approximation (GGA) and the modified Becke-Johnson potential (TB-mBJ) to enhance band gap predictions, in addition to the GGA + U method to address strong electron correlations. The compounds crystallize in a cubic structure (space group $Fm\bar{3}m$) with negative formation energies, indicating their stability.

Our results demonstrate the presence of thermodynamically stable cubic phases of Sr₂TmWO₆, all exhibiting significant mechanical and dynamical stability, as confirmed by our evaluations of elastic constants and phonon spectra. The magnetic moments of 2, 3, and 4 μ_B for Sr₂CrWO₆, Sr₂CoWO₆, and Sr₂FeWO₆ respectively, confirm their half-metallic characteristics, making them strong candidates for spintronic applications.

Furthermore, these compounds show promising optical properties for UV device applications. Their thermoelectric performance is particularly impressive, achieving ZT values close to unity over a wide temperature range, which emphasizes their potential in thermoelectric applications. This comprehensive analysis deepens our understanding of Sr₂TmWO₆ compounds and highlights their importance in advanced materials science, especially in spintronics and thermoelectrics.