Abstract
Complex oxides with a perovskite structure show many attractive characteristics for both basic research and applications. Among the perovskite oxides, the manganite displays high sensitivity to external disturbances such as magnetic fields, electric fields, currents, mechanical strain, and photo illumination. Herein, modifications of the transport of manganite heterojunctions by applying various fields like electric/magnetic field, visible light, lattice strain, have been investigated systemically.
In this work, we investigate the residual strain effect on the magnetoresistance of La0.9Ca0.1MnO3 /0.7Pb(Mg1/3Nb2/3)O3-0.3PbTiO3 (PMN-PT) heterostructures. X-ray diffraction (XRD) revealed that the ferroelectric poling remarkably modifies the in-plane tensile strain introduced. It is also found that due to poling of PMN-PT the magnetoresistance of La0.9Ca0.1MnO3 is reduced in the paramagnetic state but increased in ferromagnetic state. Heterostructures of manganite and ferroelectric provide a possibility to gain in-situ tunable structural, magnetic, and transport properties by means of piezoelectric effect.
Field Modulation on transport Properties in heterojunctions of La0.9Hf0.1MnO3 /0.05%Nb, SrTiO3 was also investigated.It demonstrates an excellent rectifying feature in a wide temperature range from 20 to 300 K. The rectifying ratio is higher than 103, which is much larger than those for other perovskite oxides-based heterojunctions. A crossover from positive to negative magnetoresistance in the La0.9Hf0.1MnO3 /0.05wt%Nb-doped SrTiO3 heterojunctions as the temperature decreases was also observed. These thin films presented persistent and stable photovoltages upon light illumination. Rapid shifts between small and large voltages corresponding to “light OFF” and “light ON” states, respectively, were observed, demonstrating reliable photo detection behavior. Such manipulative features by light irradiation exhibit great potential for use in light detectors for visible light.
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