Spectroscopic analysis for electric and magnetic properties of manganese doped cobalt nanoferrite

The investigated samples of manganese doped cobalt nanoferrites were prepared by the conventional solid-state reaction route using a planetary ball milling technique. The XRD patterns con firm their crystallinity and single-phase formation of spinel structure. The average particle size is obtained in the nanoscale range from their field emission scanning micrographs. Their spectroscopic analysis was performed from the measurement of dielectric constant and permeability for microstructural correlation. In the spectra of the modulus, the appeared peaks at a particular frequency set the boundary between long-range and short-range mobility of charge carriers in the material. The enumerated dielectric relaxation time constant is found to be a maximum at a characteristic temperature, which signifies the ferromagnetic-to-spin-glass state transition. The activation energy in the long-range mobility wing is found to be greater than that at the short-range mobility wing. The observed increasing trend in the real part of the magnetic modulus with the concentration level may be attributed to the dominance of dipolar orientations across the grain boundaries whereas it's decreasing trend is correlated with the decreasing trend in the crystallite/grain size. The temperature response of relaxation time constant, determined from the well-resolved peaks of the dispersion of imaginary part of magnetic modulus, exhibits the transformation of ferromagnetic phase to the glass transition at a particular temperature in the low-temperature regime due to ceasing of wall motion and spatially randomized spins by the freezing effects.