DFT Analysis of Sr2GdMO6 (M = Bi, Sb) Double Perovskites for Spintronics and UV Optoelectronics

초록

This study uses a computational method called Density Functional Theory (DFT) to examine the structure, electronic, optical, elastic, and magnetic properties of Sr2GdMO6 (M = Bi or Sb). The calculations revealed that both materials have a cubic crystal structure with slightly different lattice constants. Volume optimization of Sr2GdBiO6 and Sr2GdSbO6 in PM, FM, and AFM states reveals that Sr2GdBiO6 stabilizes in a non-magnetic PM phase, while Sr2GdSbO6 favors a magnetic ground state. The magnetic behavior is influenced by the B-site cation, with Bi suppressing and Sb promoting magnetic ordering. Their electronic structures reveal that Sr2GdBiO6, have band gap 2.06 eV for spin-up and 2.18 eV for spin-down. Similarly, Sr2GdSbO6, have band gap 3.26 eV for spin-up and 3.40 eV for spin-down. Optical investigations have shown strong absorption in the ultraviolet region, with peaks at 3.75 eV for Sr2GdBiO6 and 4.15 eV for Sr2GdSbO6. The materials Sr2GdBiO6 and Sr2GdSbO6 have stable mechanical properties, with bulk moduli of 112.18 GPA and 143.235 GPA, respectively. They possess a significant magnetic moment of 7 Bohr magnetons per gadolinium atom, primarily due to the contribution of its 4f electrons, indicating their strong magnetic nature. To accurately account for the interactions between electrons in these materials, a specific parameter called the Hubbard parameter (U) was adjusted to 6 electron volts (eV) for the Gd-4f orbitals. These findings demonstrate their potential applications in spintronics, ultraviolet optoelectronics, and mechanical devices.

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