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We report the fabrication of lead-free multiferroic structures by depositing ferromagnetic La0.7 Sr0.3 (LSMO) polycrystalline films on polished 0.5BaZr0.2Ti 0.8O3-0.5Ba 0.7Ca0.3TiO3 (BZT-BCT) piezoelectric ceramic substrates. By applying electric fields to the BZT-BCT along the thickness direction, the resistivity of LSMO films can be effectively manipulated via the piezoelectric strain of the BZT-BCT. Moreover, the LSMO polycrystalline films exhibit almost temperature independent and significantly enhanced magnetoresistance (MR) below TC. At T = 2K and H = 8T, the MR of polycrystalline films is approximately two orders of magnitude higher than that of LSMO epitaxial films grown on (LaAlO3)0.3(SrAl1/2Ta1/2O3)0.7 single-crystal substrates. The enhanced MR mainly results from the spin-polarized tunneling of charge carriers across grain boundaries. The LSMO/BZT-BCT structures with electric-field controllable modulation of resistivity and enhanced MR effect may have potential applications in low-energy consumption and environmentally friendly electronic devices. [ABSTRACT FROM AUTHOR]

We have fabricated magnetoelectric heterostructures by growing ferromagnetic La1-xBaxMnO3 (x=0.2, 0.4) thin films on (001)-, (110)-, and (111)-oriented 0.31Pb(In1/2Nb1/2)O3-0.35Pb(Mg1/3 Nb1/2)O3-0.34PbTiO3 (PINT) ferroelectric single-crystal substrates. Upon poling along the [001], [110], or [111] crystal direction, the electric-field-induced non-180° domain switching gives rise to a decrease in the resistance and an enhancement of the metal-to-insulator transition temperature TC of the films. By taking advantage of the 180° ferroelectric domain switching, we identify that such changes in the resistance and TC are caused by domain switching-induced strain but not domain switching-induced accumulation or depletion of charge carriers at the interface. Further, we found that the domain switching-induced strain effects can be efficiently controlled by a magnetic field, mediated by the electronic phase separation. Moreover, we determined the evolution of the strength of the electronic phase separation against temperature and magnetic field by recording the straintunability of the resistance [(ΔR/R)strain] under magnetic fields. Additionally, opposing effects of domain switching-induced strain on ferromagnetism above and below 197K for the La0.8Ba0.2MnO3 film and 150K for the La0.6Ba0.4MnO3 film, respectively, were observed and explained by the magnetoelastic effect through adjusting the magnetic anisotropy. Finally, using the reversible ferroelastic domain switching of the PINT, we realized non-volatile resistance switching of the films at room temperature, implying potential applications of the magnetoelectric heterostructure in non-volatile memory devices. [ABSTRACT FROM AUTHOR]

We report exchange bias effect in Fe3O4 films epitaxially grown on SrTiO3 substrates. This effect is related to the formation of Ti3+-vacancy complexes at the surface of SrTiO3 in ultrahigh vacuum that in turn triggers the growth of a thin antiferromagnetic (AFM) FeO layer (~5 nm) at the interface. The picture of antiferromagnetic FeO interacting with native ferrimagnetic Fe3O4 matrix reasonably accounts for this anomalous magnetic behavior. With increasing film thickness from 17 to 43 nm, the exchange bias effect and the magnetization anomaly associated with the AFM phase transition of the FeO layer are progressively weakened due to the increase in the volume fraction of the Fe3O4 phase, indicating the interfacial nature of the exchange coupling. Our results highlight the important role of interface engineering in controlling the magnetic properties of iron oxide thin films. [ABSTRACT FROM AUTHOR]

Hydrothermally synthesized piezoelectric Pb(Zr0.52Ti0.48)O3 fibers were used as a mechano-catalyzer to degrade acid orange 7 dye wastewater via the mechano-catalytic effect, which was achieved as a product of the piezoelectric effect and the electro-catalytic effect. When subjected to mechanical vibration, the Pb(Zr0.52Ti0.48)O3 fibers bend, which in turn induces electric charges on the surfaces of the fibers via the piezoelectric effect. The piezoelectrically induced electric charges induce chemical degradation reactions in the dye wastewater through the electro-catalytic effect. A high mechano-catalytic degradation ratio of ~80% was achieved for the acid orange 7 solutions (~30 μmol/l). The piezoelectrically induced mechano-catalytic effect thus provides a highly efficient and reusable technology for dye wastewater degradation applications. [ABSTRACT FROM AUTHOR]