Preparation And Properties Of Multi - Ferrous Composite Films

Magnetoelectric materials is a kind of material that integrating a variety of properties, which can not only exhibit ferroelectric, magnetic and ferroelastic properties, but also can produced novel effect by the coupling interaction between they. The coupling interaction between ferroelectric and magnetic order parameters produce magnetoelectric(ME) effect, for example. BaTiO3(BTO)/CoFe2O4(CFO) /SrRuO3(SRO) and BTO/CFO/Ta2O5/SRO were prepared through the gel-gel method, pulsed laser deposition(PLD), magnetron sputtering(MS) in this paper, and the microstructures and properties were studied.First the sol-gel method is adopted to prepare the good electrical and optical BTO thin film, the BTO film is a good insulating material, the electric resistance is at order of magnitude of 1 x 1014 ?/cm.Visible and intense photoluminescence(PL) phenomenon was also observed in the BTO thin films at room temperature. The theoretical and experimental results by PL emission suggest the presence of localized states existing inside of the band gap which are directly affected for degree of order–disorder.The UV–vis absorption spectrum indicating the BTO films had a direct band gap of about 3.02 eV.Sol-gel method prepared BTO、CFO ceramic material with good uniformity, high density, composition pure were used as targets for the preparation of films by PLD. CFO/BTO/SRO, CFO/BTO/Ta2O5/SRO composite films deposited on(? 00) orientation SrTiO3(STO) show good quality. Except that Ta2O5 is amorphous, SRO, BTO, CFO are all show(? 00) preferred orientation of the substrate.CFO/BTO/SRO 、 CFO/BTO/Ta2O5/SRO composite films show good ferroelectricity, the former is weaker than the latter, the saturated polarization are 37.3μC/cm-2 and 47.6μC/cm-2 respectively. That is to say Ta2O5 buffer layer can inhibit the interface effect between BTO and SRO, so as to improve the films’ performance. The two compound films’ magnetism can differ not quite, their saturation magnetization are 130 emu/cm3 and 127 emu/cm3 respectively.The composite films magnetoelectric coupling coefficient were theoretically analyzed and calculated, E31? is 923 mv/cm-1Oe-1 without considering the effect of substrate clamping. On considering substrate clamping effect, E31? is very small. Experiment results of the CFO/ BTO/ SRO,CFO/BTO/Ta2O5/SRO films are 1E31? = 88 mv/ cm-1,at 2E31? = 130 mv/cm-1Oe-1, respectively, indicating the high~k Ta2O5 buffer layer can inhibit the interface effect to improve composite ferroelectric thin film and reduce substrate clamping, and thus enhanced the magnetoelectric coupling performance of composite films.