Structural Stability, Half-Metallic Ferromagnetism, Magneto-Optical, and Thermoelectric Properties of Europium-Based Ternary Zintl Compounds EuZn2C2(C = P, As): A Promising Alternative for Spintronics and Thermoelectric Applications

Abstract

For optimal spintronic device performance, high spin-polarized materials are crucial to facilitate efficient spin injection from ferromagnets to semiconductors. The EuZn₂C₂ (C = P, As) Zintl compounds have been predicted to exhibit half-metallic behavior based on first-principles investigations of their structural, magneto-optical, and thermoelectric properties using the full-potential linearized augmented plane wave (FP-LAPW) method. The PBE-GGA potential was employed to obtain theoretical results consistent with available experimental data for structural determination of europium compounds, while the GGA + U, mBJ, and SOC methods were utilized to improve the accuracy of electronic and magnetic properties. A comparative analysis of the compounds in their stable ferromagnetic, paramagnetic, and antiferromagnetic phases revealed that the ferromagnetic phase is more suitable for investigating magnetic properties. The calculated density of states (DOS) and band structures showed strong hybridization between the Eu-f state and the Zn-d and (P, As)-p states in the valence band, resulting in the formation of a half-metallic gap. The orbital hybridizations (d-f, p-d, and d-d) were found to contribute to the gap formation. Moreover, the strength of exchange splitting between the e.g. and t_2g states, determined by the occupation and distribution of electronic states, was found to influence the size of the gap. The calculated total magnetic moment of the EuZn₂ × ₂ compound confirmed strong ferromagnetism. Furthermore, the effects of spin-orbit coupling on the electronic structure were investigated, and the thermoelectric properties were computed using Boltzmann transport theory. The Curie temperatures were also determined. Notably, the EuZn₂C₂ (C = P, As) Zintl compounds exhibited Curie temperatures significantly higher than room temperature, making them promising candidates for spintronic applications due to their strong ferromagnetism and metallic nature.