The effect of film/electrode interfaces on the dielectric responses of highly (000l)-oriented M-type BaFe ₁₂ O ₁₉ thin films synthesized using chemical solution deposition

Highly (000l)-oriented, M-type, hexaferrite BaFe ₁₂ O ₁₉ (BaM) thin films were fabricated on La _0.7 Sr _0.3 MnO ₃ /(111)SrTiO ₃ (LSMO/STO) and (111)Pt using chemical solution deposition. The temperature dependent dielectric properties and ac conductivity of the BaM films with different film/electrode interfaces were investigated. The results show that the chemical interfaces rather than the contact interfaces in the film/electrode played a significant role in the resulting electrical properties. For both BaM films, hopping conduction accompanied by dielectric relaxation at low frequencies was observed, which can be explained by the localized hopping of electrons through energy barriers separating different Anderson localized states, i.e., multivalent Fe sites. The X-ray photoelectron spectroscopy data confirm that the Fe ²⁺ /Fe ³⁺ ratio of the BaM/LSMO was less than that of the BaM/Pt, which might lead to more difficult hopping processes and better electrical properties.