BiFeO 3 (BFO) films were processed on BaTiO3 (BTO) buffered (111) Pt/Ti/SiO2/Si substrate by pulsed laser deposition. Improved ferroelectric properties, as well as induced ferromagnetism, were observed by the insertion of a BTO layer for rather thick BFO films (450 nm) deposited at an oxygen pressure of 40 mTorr. Reduced leakage current, coercive field, and increased ferroelectric saturation of BFO/BTO bilayer films were obtained and compared with those of BFO films. In order to better understand the buffer layer effect on the magnetic properties, two thinner (140 and 220 nm) BFO films were also deposited and investigated. Both films showed ferromagnetic hysteresis loops and larger in-plane magnetization than out-of-plane magnetization. By introducing the BTO barrier layer, the remnant and saturated magnetizations were also increased. These results demonstrated not only the interface constraint effect but also a coupling between ferroelectric BTO and magnetic BFO, which deserve further investigation.
The effects of Cr-stoichiometry on the structural, electrical and optical properties of delafossite-type CuCrO 2 thin films are reported. Thin films were grown by pulsed laser deposition on glass and c-sapphire single-crystal substrates, and the effects of increased temperature on the thin film properties were examined. The substrate temperature and oxygen partial pressure were found to be important processing parameters for fabricating delafossite thin films. The electrical properties of the thin films generally improved with increasing substrate temperature. The properties of the thin films depend on the crystallinity. The improvements in crystallinity and electrical conductivity were made by increasing the Cr-deficiency in the CuCr 1−x O 2 system. By optimising processing parameters, the electrical conductivity of a CuCr 1−x O 2 thin film was 8.30 S/cm (x = 0.00) and this increased with the introduction of Cr-deficiency to 21.03 S/cm (x = 0.03) with a mean optical transmittance of 60%. The bandgaps of the thin films ranged from approximately 3.00 to 3.22 eV.
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