Structural and magnetic properties of double perovskites Ca₂FeMn_1−xCr_xO₆ (x = 0.06 and 0.12)

The structural and magnetic properties of single-phase polycrystalline Ca₂FeMn_1−xCr_xO₆ (x = 0.06 and 0.12) double perovskites were thoroughly investigated in this study. The samples were prepared using a simple solid-state synthesis process. Rietveld analysis of the X-ray diffraction (XRD) patterns revealed a monoclinic structure with a P2₁/c space group for all samples. Several parameters, such as microstrain, density, and crystallite size were computed. Additionally, microstructure analysis showed random geometric morphologies of the grains. To determine the magnetic characteristics of these double perovskites, a temperature-dependent magnetization experiment was conducted at a magnetic field of µ₀ H = 0.01T. Antiferromagnetic (AFM)-paramagnetic (PM) transitions were observed in the samples, with Neel temperatures of around T_N = 36.40 K and 36.13 K for x = 0.06 and 0.12, respectively. Both compounds exhibit spin glass behavior. Antiferromagnetic (AFM), ferromagnetic (FM), and ferrimagnetic (FiM) ordering were among the various magnetic exchange interactions present in the system, leading to a complex magnetic response below the Neel temperature T_N. The exchange bias in the compounds contributed to the FiM and FM moment exchange coupling at the antiphase boundaries of AFM ordering. The findings on the exchange bias effect in these materials have significant technical implications for practical applications.