Magnetic and anomalous dielectric behavior of Mn modified Ba2Mg2Fe12O22 hexaferrite

Abstract

We have investigated structural, dielectric, magnetic and magnetoelectric (ME) properties of Ba2Mg2(Fe1-xMnx)12O22 (x=0, 0.04, 0.08) hexaferrite. Rietveld refinement of X-ray data confirms the phase purity with rhombohedral crystal structure (R-3m space group). An anomalous behaviour of fitted parameters obtained from dielectric and impedance spectroscopy near Tc (Curie temperature) is explained in terms of MaxwellWagner interfacial polarization effect. Mn substitution causes a substantial decrease in Tc from 647 K (parent sample) to 623 K (4% Mn doped) which is due to modification in super exchange angle of Fe at octahedral sites. Our results confirm the decrease in magnetocrystalline anisotropy constant (K) by ~54% and coercive field (Hc) by ~12 % due to formation of Bloch wall upon Mn doping. Evidence of ME coupling at room temperature is reported in all Mn doped samples.