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
The La0.67Sr0.33MnO3 +δ/Pr0.7Ca0.3MnO3 +δ/La0.67Sr0.33MnO3 +δ(LPL) trilayered films on (100)LaA-1O3 substrates are prepared by using direct current (DC) magnetron sputtering method. The results obtained by means of...The La0.67Sr0.33MnO3 +δ/Pr0.7Ca0.3MnO3 +δ/La0.67Sr0.33MnO3 +δ(LPL) trilayered films on (100)LaA-1O3 substrates are prepared by using direct current (DC) magnetron sputtering method. The results obtained by means of X-ray powder diffractometer show that all films are the high quality epitaxial films. The results gained by SQUID magnetometer indicate that there is a magnetic coupling in the LPL trilayered films. The resistivities of LSMO, PC-MO and LPL films are measured using standard four-probe method and analyzed log ρ/T curve. From the results it is concluded that the middle-layered PCMO which is ferromagnetic may play a role of intra-magnetic field, which weakens the paramagnetism of LSMO film, lowers ρmax and enlarges Tp which is the transition temperature from metal to insulator, just as the applied magnetic field does. And the middle-layered PCMO may induce the change of the density of states in the LSMO' s gap. The two reasons above make the resistivity and Tp of the samples in zero field change with the thickness of PCMO layers.展开更多
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
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 Chinese Academy of Sciences the Foundation of State ScienceTechnology Commission of China
文摘The La0.67Sr0.33MnO3 +δ/Pr0.7Ca0.3MnO3 +δ/La0.67Sr0.33MnO3 +δ(LPL) trilayered films on (100)LaA-1O3 substrates are prepared by using direct current (DC) magnetron sputtering method. The results obtained by means of X-ray powder diffractometer show that all films are the high quality epitaxial films. The results gained by SQUID magnetometer indicate that there is a magnetic coupling in the LPL trilayered films. The resistivities of LSMO, PC-MO and LPL films are measured using standard four-probe method and analyzed log ρ/T curve. From the results it is concluded that the middle-layered PCMO which is ferromagnetic may play a role of intra-magnetic field, which weakens the paramagnetism of LSMO film, lowers ρmax and enlarges Tp which is the transition temperature from metal to insulator, just as the applied magnetic field does. And the middle-layered PCMO may induce the change of the density of states in the LSMO' s gap. The two reasons above make the resistivity and Tp of the samples in zero field change with the thickness of PCMO layers.
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.
