Observation of Competing Magnetic Phases, Mechanical Stability, Electronic Structure, Magnetism, and Remarkable Thermoelectric Aspects of the Ba2GdRuO6

Abstract

The Ba2 GdRuO6 (BGRO) double perovskite oxide (DPO) demonstrates intriguing behavior, arising from competing antiferromagnetic (AFM) and ferrimagnetic (FiM) phases. Under the GGA+U+SOC scheme, the system exhibits an AFM ground state with a very small energy difference of −11.39 meV with FiM one. In contrast, spin modeling reveals significant magnetic frustrations along the z-axis and favors the FiM phase. Also, the magnetic phase transition discloses a Curie temperature (T_C) of 60 K. Additionally, magnetization measurements also affirm the FiM nature which lost saturation at higher temperatures, indicating a transition from FiM to paramagnetic above T_C. The electronic structure displays the semiconductor nature owing to a direct energy gap of 1.04/0.89 eV in the AFM/FiM state. The determined spin moments on the Gd(1-2)/Ru(1-2) and Gd(3-4)/Ru(3-4) ions are +6.9/+2.0 µB and −6.9/−2.0 µB in the AFM SO, respectively, while they are +6.89/−2.0 on the Gd(1-4)/Ru(1-4) ion in the FiM one. It is found that, Gd3+ and Ru4+ ions lie in +3(4f ^7) and +4(4d^4) alence state with the electronic configurations of [ fx(x2 −3y2 ) ]↑0 ↓1 [ fy(3x2 −y2 ) ]↑0 ↓1 [ fz(x2 −y2 ) ]↑0 ↓1 [ fxyz ]↑0 ↓1 [ fxz2 ]↑0 ↓1 [ fyz2 ]↑0 ↓1 [ fz3 ]↑0 ↓1 and 3 ↑ t 1 ↓ e0 ↑ e0 ↓ with spin quantum number of 7/2 and 1, correspondingly. Furthermore, the mehanical stability of the material is validated by satisfying the Born stability criteria and the ductility (B/G= 5.19). Noticeably, the presence of a positive Cauchy presis determined by the Pugh’s ratio of 66.53 GPa further supports the ionic nature of the motif. Besides, the system illustrates a positive Seebeck coefficient, indicating holes as the dominant charge carriers with the highest of 279 µV/K at 400 K. Remarkably, system achieves a high figure of merit of 0.86 at 550 K even with the inclusion of lattice thermal conductivity as well as sustaining excellent thermoelectric performance, suggesting a strong potential for elevated temperature energy harvesting applications along with spintronics.