Interplay of spin-charge coupling and enhanced magnetodielectric effects in Ba_0.5La_0.5Ti_0.5Mn_0.5O₃ perovskite oxide

This work presents a comprehensive study of the structural, magnetic, dielectric, and thermodynamic properties of the Ba_0.5La_0.5Ti_0.5Mn_0.5O₃ (BLTM) perovskite oxide. Synchrotron X-ray diffraction combined with Rietveld refinement confirms that BLTM crystallizes in a cubic Pm3¯m structure. AFE-SEM and EDS analyses reveal good compositional homogeneity, and Raman spectroscopy demonstrates that simultaneous A- and B-site substitution in BLTM leads to enhanced structural disorder and modified lattice dynamics. Mn L_2,3-edge X-ray absorption spectroscopy (XAS) reveals partial oxidation of Mn³⁺ to Mn⁴⁺, consistent with the formation of Mn₃O₄, while Ti L_2,3-edge XAS verifies the persistence of Ti⁴⁺ in a stable 3d⁰ electronic configuration, indicating minimal charge transfer at the Ti site. Temperature-dependent magnetic susceptibility, specific heat, and dielectric measurements collectively indicate a ferromagnetic-like transition near 13 K and a moderate magnetodielectric (MD) response, consistent with earlier reports. The BLTM exhibits a high dielectric constant of ∼ 11,800 at room temperature, which is substantially larger than that of pristine BaTiO₃ (∼ 1900). This enhancement is attributed to the increased polarizability arising from defect dipoles and interfacial polarization. At low temperatures, a distinct dielectric anomaly emerges near the magnetic ordering temperatures, accompanied by a linear variation of the MD response with the squared magnetization, consistent with higher-order magnetoelectric coupling that can occur even in centrosymmetric systems. These results confirm the structural and electronic stability of BLTM and validate the correlated magnetic and dielectric response as intrinsic features of this class of perovskite oxides.