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The room temperature and magnetic field-dependent dielectric, impedance and magnetoelectric (ME) coupling effect of polycrystalline AFe2O4/(Pb0.80Sr0.20)TiO3 (A = Mn, Ni and Co) bi-layered composite films have been investigated. The structural and microstructural analyses using the X-ray diffraction (XRD), atomic force microscopy (AFM) and scanning electron microscopy (SEM) reveal the presence of homogenous growth of both tetragonal and spinel phases without any extra phase and diffusion in the AFO/PST20 bi-layered composite films. Our results show that all composite films exhibit ferroelectric as well as considerable magnetic, indicating magnetoelectric coupling effect. Our results show that the dielectric and impedance properties of AFO/PST20 bi-layered composite films can be manipulated by the magnetic field at room temperature, also indicating the existence of magnetoelectric coupling. The impedance (Z′ and Z″) Nyquist plots show distinct electrical responses with the magnetic field. The maximum magnetoelectric coefficient (α) is found to be αME∼ 239 and ∼ 195 mV/cm/Oe for the MFO/PST20 and CFO/PST20 bi-layered composite films, respectively. The above results show that the AFO/PST20 bi-layered composite films are room-temperature multiferroic material that can be potentially used in magnetoelectric devices. [ABSTRACT FROM AUTHOR]

CoFe2O4/(Pb0.6Sr0.4)TiO3bi-layered composite film exhibits ferromagnetic and ferroelectric responses (Ms∼ 162 emu/cm3,Hc∼ 1.8 kOe, 2Pr∼ 8.6 µC/cm2and 2Ec∼ 634 kV/cm) at room temperature. The temperature dependent dielectric anomaly near magnetic phase transition temperature suggests magnetoelectric coupling effect in the composite film. The maximumMDeffect can reach as high as ∼49% at 3 kOe applied DC magnetic field. The composite film exhibits magnetoelectric voltage co-efficientαME∼ 67 mVcm−1Oe−1. The photoluminescence emission bands of the composite film have a significant blue shift as compared to those reported for CFO and PST nanostructures. [ABSTRACT FROM AUTHOR]

MnFe2O4/(Pb0.8Sr0.2)TiO3(MFO/PST20) heterostructured composite films with three different structures have been grown on Pt/TiO2/SiO2/Si substrates by metal–organic decomposition processing via spin coating technique. The structural analysis revealed that the crystal axes of the MnFe2O4are aligned with those of the PST20 ferroelectric matrix with obvious interfaces and no diffusions exist in all the three composite films. These composite films exhibit simultaneously multiferroic and magnetoelectric responses at room temperature. The growth structure of MFO and PST20 layers has an effect on multiferroic and magnetoelectric coupling behaviours of the composite films. The bi- and four-layered MFO/PST20 composite films exhibit superior ferroelectric properties compared to the tri-layered film. The increasing MFO and PST20 layers in the composite films enhance ferromagnetic properties and are closely related to the strain release in MnFe2O4phase. The MFO/PST20 bi-layered composite film shows a high magnetoelectric voltage co-efficientαE~ 194 mVcm−1Oe−1at a dc magnetic fieldHdc~ 2.5 kOe. A significant decrease inαEvalue has been observed for tri- and four- layered composite films. A close correlation between phase selective residual stress and magnetoelectric properties has been emerged. The results are reasonably encouraging for employing MnFe2O4for growing multiferroic–magnetoelectric composite films. [ABSTRACT FROM AUTHOR]

Multiferroic nanostructured composite thin films consisting of CoFe 2 O 4 (CFO) and Pb 1−x Sr x TiO3 (PST; x = 0.1, 0.2, 0.3, 0.4 and 0.5) layers have been deposited on Pt/TiO 2 /SiO 2 /Si and quartz substrates by using metallo-organic decomposition process and spin coating. The effect of Sr content on the multiferroic and optical properties have been investigated. The phase purity such as spinel structure of CFO and perovskite structure of PST has been verified by X-ray diffraction. Cross-sectional scanning electron microscopy images revealed clear interface between CFO and PST layers without any noticeable diffusion. The multiferroic properties of CFO/PST composite films have been confirmed by magnetic and ferroelectric hysteresis loops with low leakage current density. The residual strain sensitivity of multiferroic and optical properties has been observed in the composite films. The decrease in saturation magnetization and saturation polarization with increase in Sr content has been observed which could be attributed to the decrease in residual strain of CFO/PST composite films. The magnetic phase transition temperature of the CFO/PST composite films is also reduced. The optical refractive index decreases with increase of amount of Sr content. The photoluminescence spectra of the CFO/PST composite films possess a blue shift which can be attributed to the Pb and oxygen vacancies as localized sensitizing centers. We show that the multiferroic and optical properties of the CFO/PST composite films are highly sensitive to the heterostructure strains which can be controlled by Sr content. [ABSTRACT FROM AUTHOR]