Large area YBCO superconductive films prepared by d.c. magnetron sputtering have reached: T c>89 K, J c>3.5×10 6 A/cm 2 (77 K, 0 T), R s=0.25 mΩ, at 77.5 K, 9894 MHz. The microstructure an...Large area YBCO superconductive films prepared by d.c. magnetron sputtering have reached: T c>89 K, J c>3.5×10 6 A/cm 2 (77 K, 0 T), R s=0.25 mΩ, at 77.5 K, 9894 MHz. The microstructure analysis of the film showed it has fine monocrystalline structure and the crystalline perfectness is satisfactory. The oscillator, filter and antenna made from these films are good in performance. Therefore, YBCO superconductive films have great prospect in application.展开更多
Flux avalanches,prevalently existing in superconducting thin films,can cause catastrophic breakdowns of electromagnetic properties and even irreversible damage to superconducting materials.Metal coating is an effectiv...Flux avalanches,prevalently existing in superconducting thin films,can cause catastrophic breakdowns of electromagnetic properties and even irreversible damage to superconducting materials.Metal coating is an effective way to suppress the flux avalanches in superconducting thin films.Nevertheless,it is difficult to reveal the suppression mechanisms due to the challenge of effectively separating the simultaneous eddy currents and heat exchange in the metal coating.In this work,the eddy currents and heat exchange in the Ag metal coating are separated by setting a thermal insulation layer,and its inhibiting effect on the flux avalanches of the YBCO superconducting thin films is elucidated.The results indicate that eddy currents play an important part in suppressing magnetic flux avalanches,and their effect strengthens with increasing Ag thickness.Meanwhile,employing the double-exposure method,the flux avalanche velocity of YBCO superconducting thin films was measured,revealing a significant decrease in the magnetic flux avalanche velocity due to suppression by eddy currents.Moreover,a theoretical model was established to investigate the influence of eddy currents on the motion of a single vortex,and the calculated results showed good agreement with the experiments.These findings provide a better understanding of the flux avalanches and their suppression in YBCO superconducting thin films.展开更多
High quality epitaxial YBa2Cu3O7-δ （YBCO） superconducting films were fabricated on （00l） LaAlO3 substrates using the direct-current sputtering method. The attainment of an unusually high film thickness （up to 2...High quality epitaxial YBa2Cu3O7-δ （YBCO） superconducting films were fabricated on （00l） LaAlO3 substrates using the direct-current sputtering method. The attainment of an unusually high film thickness （up to 2.0 μm） without mi-crocracking was attributed in part to the presence of pores correlated with yttrium-rich composition in the films. The influ-ence of the film thickness on the microstructure was investigated by X-ray diffraction conventional scan （θ-2θ,ω-scan,pole figure） and high-resolution reciprocal space mapping. The films were c-axis oriented with no a-axis-oriented grains up to the thickness of 2 μm. The surface morphology and the critical current density （Jc） strongly depended on the film thickness. Furthermore,the reasons for these thickness dependences were elucidated in detail.展开更多
YBa2Cu3O7-δ and Tl2Ba2CaCu2O8 thin films for microwave filters were synthesized by pulsed laser deposition and the two-step thalliation process. Substrate quality requirements and the relation of thin film morphology...YBa2Cu3O7-δ and Tl2Ba2CaCu2O8 thin films for microwave filters were synthesized by pulsed laser deposition and the two-step thalliation process. Substrate quality requirements and the relation of thin film morphology, microstructure with microwave surface resistance were discussed.展开更多
High quality YBa2Cu3O6+x (YBCO) superconductive thin films have been fabricated on the SrTiO3(100) substrate using laser molecular beam epitaxy (laser-MBE).The active oxygen source was used,which made the necessary am...High quality YBa2Cu3O6+x (YBCO) superconductive thin films have been fabricated on the SrTiO3(100) substrate using laser molecular beam epitaxy (laser-MBE).The active oxygen source was used,which made the necessary ambient oxygen pressure be 2-3 orders lower than that in pulsed laser deposition (PLD).Tc0 is 85-87 K,and Jc～1.0×106 A/cm2.Atomic force microscopy (AFM) measurements show that no obvious particulates can be observed and the root mean square roughness is 7.8 nm.High stability DC superconducting quantum interference devices (DC-SQUID) was fabricated using this YBCO thin film.展开更多
文摘Large area YBCO superconductive films prepared by d.c. magnetron sputtering have reached: T c>89 K, J c>3.5×10 6 A/cm 2 (77 K, 0 T), R s=0.25 mΩ, at 77.5 K, 9894 MHz. The microstructure analysis of the film showed it has fine monocrystalline structure and the crystalline perfectness is satisfactory. The oscillator, filter and antenna made from these films are good in performance. Therefore, YBCO superconductive films have great prospect in application.
基金National Natural Science Foundation of China(No.12325205,No.12232005,U2241267,12272155)Major Scientific and Technological Special Project of Gansu Province(23ZDKA0009)Natural Science Foundation of Gansu Province of China(No.23JRRA1118).
文摘Flux avalanches,prevalently existing in superconducting thin films,can cause catastrophic breakdowns of electromagnetic properties and even irreversible damage to superconducting materials.Metal coating is an effective way to suppress the flux avalanches in superconducting thin films.Nevertheless,it is difficult to reveal the suppression mechanisms due to the challenge of effectively separating the simultaneous eddy currents and heat exchange in the metal coating.In this work,the eddy currents and heat exchange in the Ag metal coating are separated by setting a thermal insulation layer,and its inhibiting effect on the flux avalanches of the YBCO superconducting thin films is elucidated.The results indicate that eddy currents play an important part in suppressing magnetic flux avalanches,and their effect strengthens with increasing Ag thickness.Meanwhile,employing the double-exposure method,the flux avalanche velocity of YBCO superconducting thin films was measured,revealing a significant decrease in the magnetic flux avalanche velocity due to suppression by eddy currents.Moreover,a theoretical model was established to investigate the influence of eddy currents on the motion of a single vortex,and the calculated results showed good agreement with the experiments.These findings provide a better understanding of the flux avalanches and their suppression in YBCO superconducting thin films.
文摘High quality epitaxial YBa2Cu3O7-δ （YBCO） superconducting films were fabricated on （00l） LaAlO3 substrates using the direct-current sputtering method. The attainment of an unusually high film thickness （up to 2.0 μm） without mi-crocracking was attributed in part to the presence of pores correlated with yttrium-rich composition in the films. The influ-ence of the film thickness on the microstructure was investigated by X-ray diffraction conventional scan （θ-2θ,ω-scan,pole figure） and high-resolution reciprocal space mapping. The films were c-axis oriented with no a-axis-oriented grains up to the thickness of 2 μm. The surface morphology and the critical current density （Jc） strongly depended on the film thickness. Furthermore,the reasons for these thickness dependences were elucidated in detail.
基金The authors are grateful for the measurement of Rs by the University of Electronic Science andTechnology, Chengdu, and the fabrication of filters by the Institute 55, Nanjing. We are also thankful for Prof. Y. F. Chen for her useful discussion and read
文摘YBa2Cu3O7-δ and Tl2Ba2CaCu2O8 thin films for microwave filters were synthesized by pulsed laser deposition and the two-step thalliation process. Substrate quality requirements and the relation of thin film morphology, microstructure with microwave surface resistance were discussed.
基金This work was supported by the State Key Program of China (Grant No. G1998061412) the National 863 Project (Grant No. 863-CD070103) .
文摘High quality YBa2Cu3O6+x (YBCO) superconductive thin films have been fabricated on the SrTiO3(100) substrate using laser molecular beam epitaxy (laser-MBE).The active oxygen source was used,which made the necessary ambient oxygen pressure be 2-3 orders lower than that in pulsed laser deposition (PLD).Tc0 is 85-87 K,and Jc～1.0×106 A/cm2.Atomic force microscopy (AFM) measurements show that no obvious particulates can be observed and the root mean square roughness is 7.8 nm.High stability DC superconducting quantum interference devices (DC-SQUID) was fabricated using this YBCO thin film.
