In this letter, we report the photoinduced effect modulated by different electric fields in the Pr0.65 (Ca0.75Sr0.25)0.35MnO3/0.7PbMg1/3Nb2/3O3-0.3PbTiO3 heterostructure. The film exhibits a decrease in the resistance up to five orders of magnitude by enhancing applied electric fields, combined with an electric-field-induced insulator-to-metal transition. More interestingly, a reversible bistability arises in the photoinduced change in resistance at T < 80 K as the voltages are increased. The results can be attributed to the phase separation in manganites, which provides a prototype of photoelectric conversion for electric-field modulation of all-oxide heterostructures.
LaCoO3 (LCO) has attracted much attention due to the unique magnetic transition and spin transition of Co3+ ions. Epitaxial LCO film exhibits an unexpected ferromagnetism, in contrast to the non-magnetism of bulk LCO. An in-depth study on the property of strained LCO film is of great importance. We have fabricated 30 nm LCO films on various substrates and studied the magnetic and transport properties of films in different strain states (compressed strain for LCO/LaAlO3, tensile strain for LCO/(LaAlO3)0.3(Sr2TaAlO6)0.35, SrTiO3). The in-plane tensiled LCO films exhibit ferromagnetic ground state at 5K and magnetic transition with TC around 85K, while compressed LCO/LaAlO3 film has a negligibly small moment signal. Our results reveal that in-plane tensile strain and tetragonal distortion are much more favorable for stabilizing the FM order in LCO films.
Persistent magnetoresistance effects in the phase-separated Pr0.65(Ca0.25Sr0.75)0.35MnO3/SrTiO3 and Pr0.65(Ca0.25Sr0.75)0.35MnO3/0.7PbMg1/3Nb2/3O3–0.3PbTiO3 heterostructures under a low magnetic field are investigated. It is observed that the persistent magnetoresistance effects decrease with increasing temperatures and the values for the heterostructures on 0.7Pb(Mg1/3Nb2/3)O3–0.3PbTiO3 and SrTiO3 substrates are about 86.6% and 33.2% at 40 K, respectively. More interestingly, the applied electric field on the 0.7PbMg1/3Nb2/3O3–0.3PbTiO3 substrate can suppress the persistent magnetoresistance effect, indicating that different energy landscapes can be dramatically modulated by the piezo-strain. These results are discussed in terms of the strain-induced competition in the ferromagnetic state and the charge-ordering phase by the energy scenario, which provide a promising approach for designing devices of electric-magnetic memories in all-oxide heterostructures.
AB ST R ACT : In this study, poly(methyl methacrylate-maleic anhydride) (P(MMA-MAh)) was synthesized in toluene from methyl methacrylate (MMA) and maleic anhydride (MAh) monomers via free radical polymerization, in the presence of 2,2'-Azo-bis-isobutyronitrile (AIBN), as initiator at 80ºC for 8 h. The molar ratio of monomers was found to be 1 MAh:8 MMA using hydrolysis and titration. The molecular weight of co-polymer was determined to be of the order of 10 4 (g/mol) by gel permeation chromatography. The co-polymer was characterized using Fourier transform infrared and nuclear magnetic resonance spectroscopy. Thermogravimetric analysis indicated the initial decomposition temperature was~270ºC. Differential scanning calorimetry indicated that the glass transition temperature was near 126ºC.Rectorite modified with benzyldimethyldodecylammonium chloride (OREC) was used as an additive to modify gel polymer electrolytes (GPEs) which consisted of P(MMA-MAh) used as a polymer matrix, propylene carbonate (PC) as a plasticizer and LiClO 4 as the lithium ion source. X-ray diffraction analysis indicates that OREC can exfoliate well in GPEs when the amount of clay is suitable. The temperature dependence of the ionic conductivity of the resulting GPEs agreed well with the VTF (Vogel-Tamman-Fulcher) relation. OREC doses of 5 phr resulted in the greatest ionic conductivity. This OREC addition considerably improved the plasticized retention levels. As a consequence of OREC occupying the free volume space in the polymer matrix of GPEs, the bulk resistance of the GPEs was reduced and the glass transition temperature (T g ) increased.
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