High-quality superconducting FeSe0.5 Te0.5 films are epitaxiMly grown on different substrates by using the pulsed laser deposition method. By measuring the transport properties and surface morphology of films grown on...High-quality superconducting FeSe0.5 Te0.5 films are epitaxiMly grown on different substrates by using the pulsed laser deposition method. By measuring the transport properties and surface morphology of films grown on single- crystal substrates of Al2O3 （0001）, SrTiO3 （001）, and MgO （001）, as well as monitoring the real-time growth process on MgO substrates with reflection high energy electron diffraction, we find the appropriate parameters for epitaxial growth of high-quality FeSe0.5 Te0.5 thin films suitable for angle-resolved photoemission spectroscopy measurements. We further report the angle-resolved photoemission spectroscopy characterization of the super- conducting films. The clearly resolved Fermi surfaces and the band structure suggest a sample quality that is as good as that of high-quality single-crystals, demonstrating that the pulsed laser deposition method can serve as a promising technique for in situ preparation and manipulation of iron-based superconducting thin films, which may bring new prosperity to angle-resolved photoemission spectroscopy research on iron-based superconductors.展开更多
High-temperature thermoelectric transport property measurements have been performed on the highly c-axis oriented Bi2Sr2Co20v thin films prepared by pulsed laser deposition on LaA1Oa （001）. Both the electric resisti...High-temperature thermoelectric transport property measurements have been performed on the highly c-axis oriented Bi2Sr2Co20v thin films prepared by pulsed laser deposition on LaA1Oa （001）. Both the electric resistivity p and the seebeck coefficient S of the film exhibit an increasing trend with the temperature from 300 K-1000 K and reach up to 4.8 m. cm and 202 V/K at 980 K, resulting in a power factor of 0.85 mW/mK which are comparable to those of the single crystalline samples. A small polaron hopping conduction can be responsible for the conduction mechanism of the film at high temperature. The results demonstrate that the Bi2Sr2Co2Oy thin film has potential application has high temperature thin film thermoelectric devices,展开更多
Textured Bi and MnBi/Bi thin films are prepared by the pulsed laser deposition method. The highly c-axis textured MnBi films are obtained by annealing the bilayer consisting of textured Bi and Mn films. The eoerciviti...Textured Bi and MnBi/Bi thin films are prepared by the pulsed laser deposition method. The highly c-axis textured MnBi films are obtained by annealing the bilayer consisting of textured Bi and Mn films. The eoercivities of the MnBi/Bi film are 1.5 T and 2.35 T at room temperature and at 373K, respectively, showing a positive temperature coefficient. Microstructural investigations show that the textured MnBi film results from the orientated growth induced by the textured Bi under-layer.展开更多
In a seminal work, Gozar et al. reported on the high-temperature interface superconductivity in bilayers of insulating La2Cu O4 and metallic La2-xSrxCuO4(x=0.45). An interesting question to address is how general and ...In a seminal work, Gozar et al. reported on the high-temperature interface superconductivity in bilayers of insulating La2Cu O4 and metallic La2-xSrxCuO4(x=0.45). An interesting question to address is how general and robust this interface superconductivity is. In the past, the cuprate bilayers were grown in a unique atomic-layer molecular beam epitaxy system, with a Sr doping range of x≤0.47, and the atomically flat interface was thought to be indispensable. Here, we have fabricated bilayers of La2CuO4 and La2-xSrxCuO4 by pulsed laser deposition. We have tried to extend the nominal doping range of Sr from the previous maximum of 0.47 to the present1.70(the nominal Sr content in the targets). X-ray diffraction result indicates that our La2-xSrxCuO4 films with x≤0.60 have very high crystalline quality;but the film crystalline structure degrades gradually with further increasing x, and finally the structure is fully lost when x reaches 1.40 and higher. Although the film quality scatters dramatically, our experiments show that there exists superconductivity for bilayers in nearly the entire over-doped Sr range, except for a non-superconducting region at x^0.80. These observations demonstrate that the interface superconductivity in copper oxides is very general and robust.展开更多
An epitaxial ZnO thin film was entirely fabricated by pulsed laser deposition. Both the orientation and the size of the crystallites were studied. The X-ray diffraction （XRD） patterns of the film show strong c-axis ...An epitaxial ZnO thin film was entirely fabricated by pulsed laser deposition. Both the orientation and the size of the crystallites were studied. The X-ray diffraction （XRD） patterns of the film show strong c-axis oriented crystal structure with preferred （002） orientation. The Phi-sca~ XRD pattern confirms that the epitaxiM ZnO exhibits a single- domain wurtzite structure with hexagonal symmetry. In situ high-temperature XRD studies of ZnO thin film show that the crystallite size increases with increasing temperature, and （002） peaks shift systematically toward lower 20 values due to the change of lattice parameters. The lattice parameters show linear increase in their values with increasing temperature.展开更多
One of the most promising near-term applications of high T_c superconductingfilms is in the area of passive microwave devices. The most remarkable feature ofthese microwave devices is that the high-frequency surface r...One of the most promising near-term applications of high T_c superconductingfilms is in the area of passive microwave devices. The most remarkable feature ofthese microwave devices is that the high-frequency surface resistance ofsuperconducting films is smaller than that of metal thin films. The size of themicrowave devices is dictated by wavelength and the thin films are generally requiredto be not smaller than a few square centimeters. Though pulsed laser deposition展开更多
基金Supported by the Chinese Academy of Sciences under Grant No 2010Y1JB6the National Basic Research Program of China under Grant No 2010CB923000the National Natural Science Foundation of China under Grant Nos 11234014 and 11227903
文摘High-quality superconducting FeSe0.5 Te0.5 films are epitaxiMly grown on different substrates by using the pulsed laser deposition method. By measuring the transport properties and surface morphology of films grown on single- crystal substrates of Al2O3 （0001）, SrTiO3 （001）, and MgO （001）, as well as monitoring the real-time growth process on MgO substrates with reflection high energy electron diffraction, we find the appropriate parameters for epitaxial growth of high-quality FeSe0.5 Te0.5 thin films suitable for angle-resolved photoemission spectroscopy measurements. We further report the angle-resolved photoemission spectroscopy characterization of the super- conducting films. The clearly resolved Fermi surfaces and the band structure suggest a sample quality that is as good as that of high-quality single-crystals, demonstrating that the pulsed laser deposition method can serve as a promising technique for in situ preparation and manipulation of iron-based superconducting thin films, which may bring new prosperity to angle-resolved photoemission spectroscopy research on iron-based superconductors.
基金Project supported by the Young Scientists Fund of the National Natural Science Foundation of China (Grant No. 10904030)the Specialized Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20091301120002)
文摘High-temperature thermoelectric transport property measurements have been performed on the highly c-axis oriented Bi2Sr2Co20v thin films prepared by pulsed laser deposition on LaA1Oa （001）. Both the electric resistivity p and the seebeck coefficient S of the film exhibit an increasing trend with the temperature from 300 K-1000 K and reach up to 4.8 m. cm and 202 V/K at 980 K, resulting in a power factor of 0.85 mW/mK which are comparable to those of the single crystalline samples. A small polaron hopping conduction can be responsible for the conduction mechanism of the film at high temperature. The results demonstrate that the Bi2Sr2Co2Oy thin film has potential application has high temperature thin film thermoelectric devices,
基金Supported by the National Natural Science Foundation of China under Grant Nos 51171001,51371009 and 50971003the Foundation of Key Laboratory of Neutron Physics of CAEP under Grant No 2014BB02
文摘Textured Bi and MnBi/Bi thin films are prepared by the pulsed laser deposition method. The highly c-axis textured MnBi films are obtained by annealing the bilayer consisting of textured Bi and Mn films. The eoercivities of the MnBi/Bi film are 1.5 T and 2.35 T at room temperature and at 373K, respectively, showing a positive temperature coefficient. Microstructural investigations show that the textured MnBi film results from the orientated growth induced by the textured Bi under-layer.
基金supported by the National Key Research and Development Program of Ministry of Science and Technology of China (2017YFA0303002, 2016YFA0300204, and 2016YFA0300701)the Fundamental Research Funds for the Central Universities
文摘In a seminal work, Gozar et al. reported on the high-temperature interface superconductivity in bilayers of insulating La2Cu O4 and metallic La2-xSrxCuO4(x=0.45). An interesting question to address is how general and robust this interface superconductivity is. In the past, the cuprate bilayers were grown in a unique atomic-layer molecular beam epitaxy system, with a Sr doping range of x≤0.47, and the atomically flat interface was thought to be indispensable. Here, we have fabricated bilayers of La2CuO4 and La2-xSrxCuO4 by pulsed laser deposition. We have tried to extend the nominal doping range of Sr from the previous maximum of 0.47 to the present1.70(the nominal Sr content in the targets). X-ray diffraction result indicates that our La2-xSrxCuO4 films with x≤0.60 have very high crystalline quality;but the film crystalline structure degrades gradually with further increasing x, and finally the structure is fully lost when x reaches 1.40 and higher. Although the film quality scatters dramatically, our experiments show that there exists superconductivity for bilayers in nearly the entire over-doped Sr range, except for a non-superconducting region at x^0.80. These observations demonstrate that the interface superconductivity in copper oxides is very general and robust.
基金Project supported by the National Natural Science Foundation of China (Grant No.10490192)
文摘An epitaxial ZnO thin film was entirely fabricated by pulsed laser deposition. Both the orientation and the size of the crystallites were studied. The X-ray diffraction （XRD） patterns of the film show strong c-axis oriented crystal structure with preferred （002） orientation. The Phi-sca~ XRD pattern confirms that the epitaxiM ZnO exhibits a single- domain wurtzite structure with hexagonal symmetry. In situ high-temperature XRD studies of ZnO thin film show that the crystallite size increases with increasing temperature, and （002） peaks shift systematically toward lower 20 values due to the change of lattice parameters. The lattice parameters show linear increase in their values with increasing temperature.
文摘One of the most promising near-term applications of high T_c superconductingfilms is in the area of passive microwave devices. The most remarkable feature ofthese microwave devices is that the high-frequency surface resistance ofsuperconducting films is smaller than that of metal thin films. The size of themicrowave devices is dictated by wavelength and the thin films are generally requiredto be not smaller than a few square centimeters. Though pulsed laser deposition
