Perovskite-based materials can be widely used in the aerospace and transportation field. Perovskite man-ganese oxides La0.7Sr0.3MnO3 （LSMO） thin films were grown on LaAlO3 （100） and Si （100） single crystal sub-s...Perovskite-based materials can be widely used in the aerospace and transportation field. Perovskite man-ganese oxides La0.7Sr0.3MnO3 （LSMO） thin films were grown on LaAlO3 （100） and Si （100） single crystal sub-strates by the polymer-assisted chemical solution deposi-tion （PACSD） method. Electronic transport behavior, microstructure, and magnetoresistance （MR） of LSMO thin films on different substrates were investigated. The resis-tance of LSMO films fabricated on LaAlO3 substrates is smaller than that on the Si substrates. The magnetic field reduces resistance of LSMO films both on Si and LAO in the wide temperature region, when the insulator-metal transition temperature shifts to higher temperature. The low-field magnetoresistance of LSMO films on Si in low temperature range at 1 T is larger than that of LSMO films on LAO. However, the MR of LSMO film on LAO films at room-temperature is about 5.17%. The thin films are smooth and dense with uniform nanocrystal size grain. These results demonstrate that PACSD is an effective technique for producing high quality LSMO films, which is significant to improve the magnetic properties and the application of automotive sensor.展开更多
La0.7Sr0.3CoO3 (LSCO) thin films were epitaxially grown on (001)-single crystalline LaAlO3 substrates by metal organic deposition. The evolution of the crystallinity of the films having various thicknesses and obtaine...La0.7Sr0.3CoO3 (LSCO) thin films were epitaxially grown on (001)-single crystalline LaAlO3 substrates by metal organic deposition. The evolution of the crystallinity of the films having various thicknesses and obtained at various annealing temperatures is investigated using Raman spectroscopy. The Raman mode associated to the Jahn-Teller distortions in the LSCO films is found to be dependent on the annealing temperature and sensitive to the strain state evolution with film thickness. The microstructure and morphology of the obtained films were investigated using transmission electron microscopy observations on cross-sections and atomic force microscopy. The obtained films are characterized by nanocrystalline morphology, with an average roughness around 5 nm. By increasing the annealing temperature to 1000℃ and the film thickness to 100 nm, the electrical resistivity was decreased by several orders of magnitude. The film resistivity reaches approximately 2.7 × 10–4 Ω•cm in a wide interval of temperature of 77 - 320 K, making this material a promising candidate for a variety of applications.展开更多
A comparative study of the crystalline structure, magnetic properties, and transport properties of LSMO films grown on （100）-, （110）-, and （111） LaAlO3（LAO） substrates was carried out. Using atomic force micro...A comparative study of the crystalline structure, magnetic properties, and transport properties of LSMO films grown on （100）-, （110）-, and （111） LaAlO3（LAO） substrates was carried out. Using atomic force microscopy, round, rectangle, and dot surface morphologies were observed in （ 100）-, （ 110）-, and （ 111 ）-oriented LSMO films, respectively. Electrical and magnetic characterizations were performed on LSMO films of different orientation to provide evidence for the effect of strain on the magnetotransport properties. The （ 111 ）-oriented LSMO film has higher saturation magnetization and lower resistance compared with the （100）- and （110）-oriented LSMO films, which results from the smaller elastic deformation due to the larger elastic modulus along the 〈 111 〉 crystallographic direction.展开更多
La0.7Ca0.3MnO3 (LCMO) films and La0.7Ca0.3MnO3/Gd0.7Ca0.3MnO3 (LCMO/GCMO) multilayers have been prepared by pulsed laser deposition. The microstructures of both systems were investigated by transmission electron micr...La0.7Ca0.3MnO3 (LCMO) films and La0.7Ca0.3MnO3/Gd0.7Ca0.3MnO3 (LCMO/GCMO) multilayers have been prepared by pulsed laser deposition. The microstructures of both systems were investigated by transmission electron microscopy (TEM). The main structure of the films and the multilayers was monoclinic with a unit cell of size 2ap x-2ap. x -2ap, where ap is the lattice constant of single perovskite crystal. The LCMO films were composed of three-dimension multitwinning domains, while the LCMO/GCMO multilayers showed two-domain structure. In LCMO/GCMO multilayers, LCMO layers were coherent with GCMO layers and the interfaces between LCMO and GCMO layers were free from mismatch dislocation, which resulted in highly strained multilayerd structures.展开更多
The magnetron sputtered La0.7Sr0.3MnO3 films were implanted with different doses (5 ′ 1015 ions×cm?2 and 5 ′ 1016 ions×cm-2) of Al ions at different negative pulsed voltages (30 kV and 50 kV) by plasma bas...The magnetron sputtered La0.7Sr0.3MnO3 films were implanted with different doses (5 ′ 1015 ions×cm?2 and 5 ′ 1016 ions×cm-2) of Al ions at different negative pulsed voltages (30 kV and 50 kV) by plasma based ion implantation and then annealed at 973 K for 1 h in air. The microstructure, surface morphologies, surface roughness, metal-insulator transition and room temperature emittance properties of the post-implantation annealed films were investigated and compared with those of the La0.7Sr0.3MnO3 film annealed at 973 K for 1 h in air. The results indicate that the post- implantation annealed films show single perovskite phase and obvious (100) preferred orientation growth. The Mn-O bond length, surface roughness and metal-insulator transition temperature (TMI) of the films can be effectively adjusted by changing implantation voltage or implantation dose of Al ions. However, the change of implantation parameters just has a small effect on room temperature emittance of the films. Compared with the annealed film, the post-implantation annealed films have shorter Mn-O bond length and lower room temperature emittance. The TMI of the films implanted at low voltage is lower than that of the annealed film, which mainly results from the degradation of oxidization during annealing process and the part displacement of Mn3+-O2+- Mn4+ double exchange channels by Al3+-O2?-Mn4+. The post-implanted annealed film implanted at 50 kV/5 ′ 1016 ions×cm-2 has a higher TMI than the annealed film, which is 247 K. The increase of TMI of the film implanted with high dose of Al ions at high voltage can be attributed to the improvement of microstructure.展开更多
基金supported by the Program of International S&T Cooperation 2013DFA51050National Magnetic Confinement Fusion Science Program (2011GB112001)+2 种基金Science Foundation of Sichuan Province (2011JY0031, 2011JY0130)the financial support of the National Natural Science Foundation of China (No. 51271155, No. 51002125)the Fundamental Research Funds for the Central Universities (SWJTU12CX018)
文摘Perovskite-based materials can be widely used in the aerospace and transportation field. Perovskite man-ganese oxides La0.7Sr0.3MnO3 （LSMO） thin films were grown on LaAlO3 （100） and Si （100） single crystal sub-strates by the polymer-assisted chemical solution deposi-tion （PACSD） method. Electronic transport behavior, microstructure, and magnetoresistance （MR） of LSMO thin films on different substrates were investigated. The resis-tance of LSMO films fabricated on LaAlO3 substrates is smaller than that on the Si substrates. The magnetic field reduces resistance of LSMO films both on Si and LAO in the wide temperature region, when the insulator-metal transition temperature shifts to higher temperature. The low-field magnetoresistance of LSMO films on Si in low temperature range at 1 T is larger than that of LSMO films on LAO. However, the MR of LSMO film on LAO films at room-temperature is about 5.17%. The thin films are smooth and dense with uniform nanocrystal size grain. These results demonstrate that PACSD is an effective technique for producing high quality LSMO films, which is significant to improve the magnetic properties and the application of automotive sensor.
文摘La0.7Sr0.3CoO3 (LSCO) thin films were epitaxially grown on (001)-single crystalline LaAlO3 substrates by metal organic deposition. The evolution of the crystallinity of the films having various thicknesses and obtained at various annealing temperatures is investigated using Raman spectroscopy. The Raman mode associated to the Jahn-Teller distortions in the LSCO films is found to be dependent on the annealing temperature and sensitive to the strain state evolution with film thickness. The microstructure and morphology of the obtained films were investigated using transmission electron microscopy observations on cross-sections and atomic force microscopy. The obtained films are characterized by nanocrystalline morphology, with an average roughness around 5 nm. By increasing the annealing temperature to 1000℃ and the film thickness to 100 nm, the electrical resistivity was decreased by several orders of magnitude. The film resistivity reaches approximately 2.7 × 10–4 Ω•cm in a wide interval of temperature of 77 - 320 K, making this material a promising candidate for a variety of applications.
基金Project supported bythe Key Basic Research Project of MOST(2002CCC01300) the Natural Science Foundation of Beijing(2021003) the Science &Technology Development Project of Beijing Education Committee and Beijing Specific Projectto Foster Elitist (20041D0501513)
文摘A comparative study of the crystalline structure, magnetic properties, and transport properties of LSMO films grown on （100）-, （110）-, and （111） LaAlO3（LAO） substrates was carried out. Using atomic force microscopy, round, rectangle, and dot surface morphologies were observed in （ 100）-, （ 110）-, and （ 111 ）-oriented LSMO films, respectively. Electrical and magnetic characterizations were performed on LSMO films of different orientation to provide evidence for the effect of strain on the magnetotransport properties. The （ 111 ）-oriented LSMO film has higher saturation magnetization and lower resistance compared with the （100）- and （110）-oriented LSMO films, which results from the smaller elastic deformation due to the larger elastic modulus along the 〈 111 〉 crystallographic direction.
基金NAMCC under Grant86&715-014-0070 and NSFC under Grant 59601002 and59831020.
文摘La0.7Ca0.3MnO3 (LCMO) films and La0.7Ca0.3MnO3/Gd0.7Ca0.3MnO3 (LCMO/GCMO) multilayers have been prepared by pulsed laser deposition. The microstructures of both systems were investigated by transmission electron microscopy (TEM). The main structure of the films and the multilayers was monoclinic with a unit cell of size 2ap x-2ap. x -2ap, where ap is the lattice constant of single perovskite crystal. The LCMO films were composed of three-dimension multitwinning domains, while the LCMO/GCMO multilayers showed two-domain structure. In LCMO/GCMO multilayers, LCMO layers were coherent with GCMO layers and the interfaces between LCMO and GCMO layers were free from mismatch dislocation, which resulted in highly strained multilayerd structures.
文摘The magnetron sputtered La0.7Sr0.3MnO3 films were implanted with different doses (5 ′ 1015 ions×cm?2 and 5 ′ 1016 ions×cm-2) of Al ions at different negative pulsed voltages (30 kV and 50 kV) by plasma based ion implantation and then annealed at 973 K for 1 h in air. The microstructure, surface morphologies, surface roughness, metal-insulator transition and room temperature emittance properties of the post-implantation annealed films were investigated and compared with those of the La0.7Sr0.3MnO3 film annealed at 973 K for 1 h in air. The results indicate that the post- implantation annealed films show single perovskite phase and obvious (100) preferred orientation growth. The Mn-O bond length, surface roughness and metal-insulator transition temperature (TMI) of the films can be effectively adjusted by changing implantation voltage or implantation dose of Al ions. However, the change of implantation parameters just has a small effect on room temperature emittance of the films. Compared with the annealed film, the post-implantation annealed films have shorter Mn-O bond length and lower room temperature emittance. The TMI of the films implanted at low voltage is lower than that of the annealed film, which mainly results from the degradation of oxidization during annealing process and the part displacement of Mn3+-O2+- Mn4+ double exchange channels by Al3+-O2?-Mn4+. The post-implanted annealed film implanted at 50 kV/5 ′ 1016 ions×cm-2 has a higher TMI than the annealed film, which is 247 K. The increase of TMI of the film implanted with high dose of Al ions at high voltage can be attributed to the improvement of microstructure.
