Dielectric relaxation and polaronic conduction in epitaxial BaFe 12 O 19 hexaferrite thin film

The dielectric properties of epitaxial BaFe 12 O 19 hexaferrite thin film have been investigated as a function of frequency (50 Hz − 2 MHz) and temperature (100–375 K). The frequency dependent permittivity, impedance ( ) and modulus ( ) spectra show that the dielectric responses of BaFe 12 O 19 thin film are thermally activated. The activation energy of BaFe 12 O 19 film ( E a ) is much smaller than that of the polycrystalline bulk BaFe 12 O 19 . In addition, E a increases with increasing temperature and there is a distribution of relaxation time in the sample. The scaling behavior of and spectra of the sample further suggest that the distribution of relaxation time is temperature independent at low temperatures (<250 K) and temperature dependent at high temperatures. The temperature dependent dc conductivity shows that small polaron hopping is the most probable conduction mechanism for BaFe 12 O 19 film.