Magnetic ordering evolution in mixed transition-metal silicate oxides Mn2MSiO6 (M = Ni, Cu, Zn): Role of d-electron occupation in the AFM–FM transition

This study explores the magnetic and electronic properties of the Mn 2 MSiO 6 (M = Ni, Cu, Zn) series of modified double perovskites using first-principles density functional theory (DFT) calculations. The structural analysis shows a consistent increase in lattice parameters, ranging from 7.20 Å for Mn 2 NiSiO 6 to 7.40 Å for Mn 2 ZnSiO 6 , which aligns with the ionic radii of the substituted cations. The magnetic ground state varies with composition: Mn 2 NiSiO 6 and Mn 2 CuSiO 6 prefer an antiferromagnetic (AFM2) order, with energy differences ( Δ E ) of 164.19 meV and 60.70 meV compared to the ferromagnetic (FM) state, while Mn 2 ZnSiO 6 exhibits a ferromagnetic ground state ( Δ E = − 92.11 meV). The magnetic moments are primarily located on the Mn ions (4.62 μ B ), with minor contributions from the oxygen and M-site atoms. Electronic structure calculations indicate metallic behavior with pronounced spin polarization near the Fermi level, mainly due to Mn 3 d states. The exchange coupling analysis identifies distinct interactions: Mn 2 NiSiO 6 exhibits strong competing couplings with J 3 = 404.92 meV, whereas Mn 2 ZnSiO 6 shows a dominant FM coupling with J 1 = 79.61 meV. Mean-field calculations estimate Néel temperatures of approximately 317.57 K for Mn 2 NiSiO 6 and 117.41 K for Mn 2 CuSiO 6 . Overall, M-site substitution in Mn 2 MSiO 6 provides a means to tune magnetic order and electronic properties, suggesting their use in spintronic applications.