Growth and characterization of textured YBaCo2O5 + δ thin films grown on (001)-SrTiO3 via DC magnetron sputtering

Abstract

Thin films of the layered cobaltite YBaCo2O5+δ were successfully grown on (001)-oriented SrTiO3 single-crystal substrates by means of DC magnetron sputtering. The 112 phase of the compound was stabilized by choosing an adequate Co reactant and through careful thermal treatment of the target. The results demonstrate the strong influence of these variables on the final phase of the compound. A substrate temperature of 1053K and an oxygen pressure of 300Pa seemed to be appropriate growing conditions for depositing (00ℓ)-textured YBaCo2O5+δ thin films onto the chosen substrate. In like fashion to the polycrystalline YBaCo2O5+δ, the films showed a clear sequence of antiferromagnetic–ferromagnetic–paramagnetic transitions within a narrow temperature range. Well-defined hysteresis loops were observed at temperatures as high as 270K, which supports the existence of a FM order in the films. In turn, the dependence of the resistivity on the temperature shows a semiconductor-like behavior, without any distinguishable structure, within the temperature range measured (50–350K). The analysis of the experimental data showed that the transport mechanism in the films is well described by using the Mott variable range hopping (VRH) conduction model.