Double-microbridge de superconducting quantum interference devices(SQUIDs)have been fabricated from the postannealed Y_(1)Ba_(2)Cu_(3)O_(y) and Tl_(2)-Ba_(2)Ca_(2)Cu_(3)O_(y) thin films by chemical etching and ion mil...Double-microbridge de superconducting quantum interference devices(SQUIDs)have been fabricated from the postannealed Y_(1)Ba_(2)Cu_(3)O_(y) and Tl_(2)-Ba_(2)Ca_(2)Cu_(3)O_(y) thin films by chemical etching and ion milling patterning technique.The applied magnetic field dependences of the voltage of the YBCO and TBCCO SQUIDs have been studied at temperature ranging from 4.2 to 23K and at 77K.The largest output voltage of the devices were 3.4μV/Φ_(0 )(at 5K)for YBCO and 60μV/Φ_(0)(at 77K)for TBCCO.The properties of the output of these devices have been discussed.展开更多
Nonequilibrium superconductivity and intermediate states in Sn-Sn-PbBi system have been studied in different sample surroundings of vacuum,gas helium,and liquid helium.General behaviors under quasiparticle injection a...Nonequilibrium superconductivity and intermediate states in Sn-Sn-PbBi system have been studied in different sample surroundings of vacuum,gas helium,and liquid helium.General behaviors under quasiparticle injection are presented.Nonequilibrium quasiparticle distribution function is modeled by the μ^(*)-T^(*) scheme,and the phonon trapping factor τ_(es)/τ_(B) is calculated through R-T equations.展开更多
High temperature superconducting Bi(Pb)-Sr-Ca-Cu-O thin films have been deposited onto single crystals(100)MgO substrates heated at 400℃ by ion beam sputtering and were post annealed in air.The film properties are se...High temperature superconducting Bi(Pb)-Sr-Ca-Cu-O thin films have been deposited onto single crystals(100)MgO substrates heated at 400℃ by ion beam sputtering and were post annealed in air.The film properties are sensitive to the annealing conditions.The best films show an onset transition temperature of approximately 120K and zero resistance at 105K.X-ray diffraction shows the films to have high c-axis orientation with a high Tc phase.The composition of film was determined by inductively coupled plasma-atomic emission spectrometry analysis,and their morphology was observed by scanning electron microscopy.展开更多
Josephson effects have been observed in Nb/YBa_(2)Cu_(3)O_(7-δ) point contacts and YBa_(2)Cu_(3)O_(7-δ) break junctions.When the junctions are exposed to a microwave field,the I-V characteristics show constant volta...Josephson effects have been observed in Nb/YBa_(2)Cu_(3)O_(7-δ) point contacts and YBa_(2)Cu_(3)O_(7-δ) break junctions.When the junctions are exposed to a microwave field,the I-V characteristics show constant voltage steps,the heights of which follow the Bessel function behavior.Obvious asymmetry about zero bias has been observed in YBCO break junctions which,we suggest,may possibly result from flux trapping in the complicated weak link structure of the system.Micrmave-induced sub-steps have also been found in YBCO break junctions.All experiments were conducted at liquid helium temperature.展开更多
A single-channel high-Tc dc-SQUID magnetometer and gradiometer have been developed to record the magnetic field component perpendicular to the human chest generated by heart-beat. Magnetocardiogram (MCG) measurements ...A single-channel high-Tc dc-SQUID magnetometer and gradiometer have been developed to record the magnetic field component perpendicular to the human chest generated by heart-beat. Magnetocardiogram (MCG) measurements have been carried out inside a magnetically shielded room. By sequentially adjusting a non-magnetic patient table with 5 cm pitch in X and Y directions, the field signals on a rectangle grid 5×5 over the chest area were registered in real time trace point by point with a typical dwell time over 30 cardiocycles each. Utilizing standard electrocardiogram (ECG) recordings as timing reference measured simultaneously with the MCG signals, the MCG data were then averaged and combined to form magnetic field patterns every 10 ms or so. Both the current dipole, which is parallel to MCG measuring plane and produces the vertical magnetic field, and its depth were determined as a function of time in a standard way. We have compared the MCG of healthy hearts with that of a heart with right bundle展开更多
文摘Double-microbridge de superconducting quantum interference devices(SQUIDs)have been fabricated from the postannealed Y_(1)Ba_(2)Cu_(3)O_(y) and Tl_(2)-Ba_(2)Ca_(2)Cu_(3)O_(y) thin films by chemical etching and ion milling patterning technique.The applied magnetic field dependences of the voltage of the YBCO and TBCCO SQUIDs have been studied at temperature ranging from 4.2 to 23K and at 77K.The largest output voltage of the devices were 3.4μV/Φ_(0 )(at 5K)for YBCO and 60μV/Φ_(0)(at 77K)for TBCCO.The properties of the output of these devices have been discussed.
文摘Nonequilibrium superconductivity and intermediate states in Sn-Sn-PbBi system have been studied in different sample surroundings of vacuum,gas helium,and liquid helium.General behaviors under quasiparticle injection are presented.Nonequilibrium quasiparticle distribution function is modeled by the μ^(*)-T^(*) scheme,and the phonon trapping factor τ_(es)/τ_(B) is calculated through R-T equations.
基金Supported by the National Center of China for Research and Development on Superconductivity.
文摘High temperature superconducting Bi(Pb)-Sr-Ca-Cu-O thin films have been deposited onto single crystals(100)MgO substrates heated at 400℃ by ion beam sputtering and were post annealed in air.The film properties are sensitive to the annealing conditions.The best films show an onset transition temperature of approximately 120K and zero resistance at 105K.X-ray diffraction shows the films to have high c-axis orientation with a high Tc phase.The composition of film was determined by inductively coupled plasma-atomic emission spectrometry analysis,and their morphology was observed by scanning electron microscopy.
文摘Josephson effects have been observed in Nb/YBa_(2)Cu_(3)O_(7-δ) point contacts and YBa_(2)Cu_(3)O_(7-δ) break junctions.When the junctions are exposed to a microwave field,the I-V characteristics show constant voltage steps,the heights of which follow the Bessel function behavior.Obvious asymmetry about zero bias has been observed in YBCO break junctions which,we suggest,may possibly result from flux trapping in the complicated weak link structure of the system.Micrmave-induced sub-steps have also been found in YBCO break junctions.All experiments were conducted at liquid helium temperature.
基金the National Center for R&D on Superconductivity, Chinese Academy of Sciences (Grant No. KJCX2-W4)the Ministry of Science and Technology of China (Grant No. G19990646).
文摘A single-channel high-Tc dc-SQUID magnetometer and gradiometer have been developed to record the magnetic field component perpendicular to the human chest generated by heart-beat. Magnetocardiogram (MCG) measurements have been carried out inside a magnetically shielded room. By sequentially adjusting a non-magnetic patient table with 5 cm pitch in X and Y directions, the field signals on a rectangle grid 5×5 over the chest area were registered in real time trace point by point with a typical dwell time over 30 cardiocycles each. Utilizing standard electrocardiogram (ECG) recordings as timing reference measured simultaneously with the MCG signals, the MCG data were then averaged and combined to form magnetic field patterns every 10 ms or so. Both the current dipole, which is parallel to MCG measuring plane and produces the vertical magnetic field, and its depth were determined as a function of time in a standard way. We have compared the MCG of healthy hearts with that of a heart with right bundle
