The interfacial electrical potentials and charge distributions of two manganite-based heterojunctions, i.e.,La_(0.67)Ca_(0.33)MnO_3/SrTiO_3:0.05 wt% Nb(LCMO/STON) and La_(0.67)Ca_(0.33)MnO_3/LaMnO_3/SrTiO_3:0.05 wt% N...The interfacial electrical potentials and charge distributions of two manganite-based heterojunctions, i.e.,La_(0.67)Ca_(0.33)MnO_3/SrTiO_3:0.05 wt% Nb(LCMO/STON) and La_(0.67)Ca_(0.33)MnO_3/LaMnO_3/SrTiO_3:0.05 wt% Nb(simplified as LCMO/LMO/STON), are studied by means of off-axis electron holography in a transmission electron microscope.The influences of buffer layer on the microstructure and magnetic properties of the LCMO films are explored. The results show that when a buffer layer of LaMnO_3 is introduced, the tensile strain between the STON substrate and LCMO film reduces, misfit dislocation density decreases near the interfaces of the heterojunctions, and a positive magnetoresistance is observed. For the LCMO/STON junction, positive and negative charges accumulate near the interface between the substrate and the film. For the LCMO/LMO/STON junction, a complex charge distribution takes place across the interface, where notable negative charges accumulate. The difference between the charge distributions near the interface may shed light on the observed generation of positive magnetoresistance in the junction with a buffer layer.展开更多
La0.67Ca0.33MnO3 thin films are fabricated on fluorine-doped tin oxide conducting glass substrates by a pulsed laser deposition technique with SrTiO3 used as a buffer layer. The current-voltage characteristics of the ...La0.67Ca0.33MnO3 thin films are fabricated on fluorine-doped tin oxide conducting glass substrates by a pulsed laser deposition technique with SrTiO3 used as a buffer layer. The current-voltage characteristics of the heterojunetions exhibit an asymmetric and resistance switching behaviour. A homogeneous interface-type conduction mechanism is also reported using impedance spectroscopy. The spatial homogeneity of the charge carrier distribution leads to field- induced potential-barrier change at the Au-La0.67Ca0.33MnO3 interface and a concomitant resistance switching effect. The ratio of the high resistance state to the low resistance state is found to be as high as 1.3 x 10^4% by simulating the AC electric field. This colossal resistance switching effect will greatly improve the signal-to-noise ratio in nonvolatile memory applications.展开更多
Systematic studies of the transport properties of La0.67Ca0.33Mn1- FexO3 (x=0?0.3) systems showed that with x increasing Fe-doping content x the resistance increases and the insulator-metal transition temperature move...Systematic studies of the transport properties of La0.67Ca0.33Mn1- FexO3 (x=0?0.3) systems showed that with x increasing Fe-doping content x the resistance increases and the insulator-metal transition temperature moves to lower temperature. For small doping content, the transport property satisfies metal transport behavior below the transition tem- perature, and above the transition temperature it satisfies the small polaron model. This behavior can be explained by Fe3+ doping, which easily forms Fe3+-O2 -Mn4+channel, suppressing the double exchange Mn3+-O2 -Mn4+ channel and enhancing ? ? the spin scattering of Mn ions induced by antiferromagnetic clusters of Fe ions.展开更多
基金supported by National Natural Science Foundation of China(50902062)the Scientific Research Foundation for the Returned Overseas Chinese Scholars of Ministry of Education
基金Project supported by the National Natural Science Foundation of China(Grant No.10974105)the High-end Foreign Experts Recruitment Programs,China(Grant Nos.GDW20173500154 and GDW20163500110)+3 种基金the Taishan Scholar Program of Shandong ProvinceShandong Province "Double–Hundred Talent Plan" on 100 Foreign Experts and 100 Foreign Expert Teams Introduction Projectthe Top-notch Innovative Talent Program of Qingdao City,China(Grant No.13-CX-08)the Qingdao International Center for Semiconductor Photoelectric Nanomaterials,and Shandong Provincial University Key Laboratory of Optoelectrical Material Physics and Devices
文摘The interfacial electrical potentials and charge distributions of two manganite-based heterojunctions, i.e.,La_(0.67)Ca_(0.33)MnO_3/SrTiO_3:0.05 wt% Nb(LCMO/STON) and La_(0.67)Ca_(0.33)MnO_3/LaMnO_3/SrTiO_3:0.05 wt% Nb(simplified as LCMO/LMO/STON), are studied by means of off-axis electron holography in a transmission electron microscope.The influences of buffer layer on the microstructure and magnetic properties of the LCMO films are explored. The results show that when a buffer layer of LaMnO_3 is introduced, the tensile strain between the STON substrate and LCMO film reduces, misfit dislocation density decreases near the interfaces of the heterojunctions, and a positive magnetoresistance is observed. For the LCMO/STON junction, positive and negative charges accumulate near the interface between the substrate and the film. For the LCMO/LMO/STON junction, a complex charge distribution takes place across the interface, where notable negative charges accumulate. The difference between the charge distributions near the interface may shed light on the observed generation of positive magnetoresistance in the junction with a buffer layer.
基金supported by the National Natural Science Foundation of China (Grant No. 60976016)the Program for Innovative Research Team in Science and Technology in University of Henan Province (IRTSTHN),China (Grant No. 2012IRTSTHN004)the Research Program of Henan University, China (Grant No. SBGJ090503)
文摘La0.67Ca0.33MnO3 thin films are fabricated on fluorine-doped tin oxide conducting glass substrates by a pulsed laser deposition technique with SrTiO3 used as a buffer layer. The current-voltage characteristics of the heterojunetions exhibit an asymmetric and resistance switching behaviour. A homogeneous interface-type conduction mechanism is also reported using impedance spectroscopy. The spatial homogeneity of the charge carrier distribution leads to field- induced potential-barrier change at the Au-La0.67Ca0.33MnO3 interface and a concomitant resistance switching effect. The ratio of the high resistance state to the low resistance state is found to be as high as 1.3 x 10^4% by simulating the AC electric field. This colossal resistance switching effect will greatly improve the signal-to-noise ratio in nonvolatile memory applications.
基金Project supported by the National Natural Science Foundation ofChina (No. 10274049) Foundation of the Natural Science of Zhe-jiang Province (Nos. RC015056 and 502122) Science & Tech-nology Development Foundation of the Education Committee of Sh-anghai Municipality (No. 02AK42)and the Shanghai LeadingAcademic Discipline Program (No. 01A16)
文摘Systematic studies of the transport properties of La0.67Ca0.33Mn1- FexO3 (x=0?0.3) systems showed that with x increasing Fe-doping content x the resistance increases and the insulator-metal transition temperature moves to lower temperature. For small doping content, the transport property satisfies metal transport behavior below the transition tem- perature, and above the transition temperature it satisfies the small polaron model. This behavior can be explained by Fe3+ doping, which easily forms Fe3+-O2 -Mn4+channel, suppressing the double exchange Mn3+-O2 -Mn4+ channel and enhancing ? ? the spin scattering of Mn ions induced by antiferromagnetic clusters of Fe ions.
