A superconducting quantum interference device(squid)was made from TlBa-CaCuO(TBCCO)thin film.The squid loop forms a part of the pickup loop.The squid hole is a square of about 100x100μm.The pickup loop and the squid ...A superconducting quantum interference device(squid)was made from TlBa-CaCuO(TBCCO)thin film.The squid loop forms a part of the pickup loop.The squid hole is a square of about 100x100μm.The pickup loop and the squid loop inductances are estimated to be 11 nH and 190pH,respectively.The best value of equivalent flux noise as measured in the flux locked loop mode is 4×10^(-4)Ф_(0)/Hz^(1/2) at dc-1 Hz.The corresponding sensitivity resolution at this frequency is 9pT/Hz^(1/2),about a factor 8 higher than the squid loop area.展开更多
We have prepared single-phase superconducting T_(12)CaBa_(2)Cu_(2)O_(8) thin film by dc magnetron sputtering process and measured X-ray photoelectron spectra of the film at room and liquid nitrogen temperatures.From t...We have prepared single-phase superconducting T_(12)CaBa_(2)Cu_(2)O_(8) thin film by dc magnetron sputtering process and measured X-ray photoelectron spectra of the film at room and liquid nitrogen temperatures.From the relative intensities of the Ba3d,Tl4f.O1 s and Cu2p spectra taken at different take-off angles,we have concluded that there is an adventitious contamination(nonsupercon-ducting phase)surface layer.After excluding contributions from these spurious phases,we have tentatively assigned which core-level shifts should be caused by the superconducting phase transition.展开更多
A high-temperature superconducting （HTS） filter subsystem consisting of a 10-pole HTS filter with group delay self-equalization, a cryogenic low noise amplifier （LNA）, and a cooling device is presented in this pap...A high-temperature superconducting （HTS） filter subsystem consisting of a 10-pole HTS filter with group delay self-equalization, a cryogenic low noise amplifier （LNA）, and a cooling device is presented in this paper. The HTS filter has a 0.51% fractional bandwidth at 1955 MHz, simulated in Sonnet, and is fabricated using double-sided TI2Ba2CaCu208 films on 0.5 mm thick LaAIO3 substrate. Measured responses show that the minimum insertion loss of the filter is 0.16 dB, and the out-of-band rejection is better than 75 dB. The slope is 27 dB MHz^-1 at the low band edge and 22 dB MHz-1 at the upper band edge. The HTS filter subsystem has a gain of 19.3 dB and a noise figure （NF） of 0.8 dB. Furthermore, the phase distortion of HTS filters is considered, and an efficient design approach for self-equalized HTS filters is proposed.展开更多
A new circuit model for designing and manufacturing an S-band low noise amplifier(LNA) with the software,Advanced Design System(ADS),is introduced in this paper.The proposed model involves shunted impedance at the gri...A new circuit model for designing and manufacturing an S-band low noise amplifier(LNA) with the software,Advanced Design System(ADS),is introduced in this paper.The proposed model involves shunted impedance at the grid to achieve a stable LNA without measuring the S-parameters of transistors at low temperatures.The LNA was measured over the operation band of 2.2-2.3 GHz,which has input and output standing wave ratios below 1.2.The noise figure of the manufactured LNA was about 0.2 dB and the gain was above 22 dB,which indicated that our LNA worked well at 77 K.展开更多
The voltage-biased current-voltage （I-V） characteristics of intrinsic Josephson junctions （IJJs）, which are fabricated with misa- ligned high temperature superconducting Tl2Ba2CaCu2O8 （T1-2212） thin film, are in...The voltage-biased current-voltage （I-V） characteristics of intrinsic Josephson junctions （IJJs）, which are fabricated with misa- ligned high temperature superconducting Tl2Ba2CaCu2O8 （T1-2212） thin film, are investigated experimentally. Three charac- teristic regions in the I-V curve are observed at 47 K. In the low voltage part, the current firstly increases and then decreases slowly with increasing the biased voltage, which is shown as a bump. In the next region, the current slightly increases with in- creasing the biased voltage until a sudden decrease of the current appears. Thereafter, branch structure forms with increasing the voltage on the I-V characteristic. The influence of the self-heating on the I-V characteristics is investigated and the temper- ature dependence of the I-V characteristics is measured to explore these characteristics in detail.展开更多
文摘A superconducting quantum interference device(squid)was made from TlBa-CaCuO(TBCCO)thin film.The squid loop forms a part of the pickup loop.The squid hole is a square of about 100x100μm.The pickup loop and the squid loop inductances are estimated to be 11 nH and 190pH,respectively.The best value of equivalent flux noise as measured in the flux locked loop mode is 4×10^(-4)Ф_(0)/Hz^(1/2) at dc-1 Hz.The corresponding sensitivity resolution at this frequency is 9pT/Hz^(1/2),about a factor 8 higher than the squid loop area.
文摘We have prepared single-phase superconducting T_(12)CaBa_(2)Cu_(2)O_(8) thin film by dc magnetron sputtering process and measured X-ray photoelectron spectra of the film at room and liquid nitrogen temperatures.From the relative intensities of the Ba3d,Tl4f.O1 s and Cu2p spectra taken at different take-off angles,we have concluded that there is an adventitious contamination(nonsupercon-ducting phase)surface layer.After excluding contributions from these spurious phases,we have tentatively assigned which core-level shifts should be caused by the superconducting phase transition.
基金Supported by the Major State Basic Research Development Program of China (973 Program) (Grant No. 2006CB601006)the National High Technology Research and Development Program of China (863 Program) (Grant No. 2006AA03Z213)
文摘A high-temperature superconducting （HTS） filter subsystem consisting of a 10-pole HTS filter with group delay self-equalization, a cryogenic low noise amplifier （LNA）, and a cooling device is presented in this paper. The HTS filter has a 0.51% fractional bandwidth at 1955 MHz, simulated in Sonnet, and is fabricated using double-sided TI2Ba2CaCu208 films on 0.5 mm thick LaAIO3 substrate. Measured responses show that the minimum insertion loss of the filter is 0.16 dB, and the out-of-band rejection is better than 75 dB. The slope is 27 dB MHz^-1 at the low band edge and 22 dB MHz-1 at the upper band edge. The HTS filter subsystem has a gain of 19.3 dB and a noise figure （NF） of 0.8 dB. Furthermore, the phase distortion of HTS filters is considered, and an efficient design approach for self-equalized HTS filters is proposed.
基金supported by the Specialized Research Fund for Doctoral Program of Higher Education in China(200800551009)the National High Technology Research and Development Program of China(2009AA03Z208)
文摘A new circuit model for designing and manufacturing an S-band low noise amplifier(LNA) with the software,Advanced Design System(ADS),is introduced in this paper.The proposed model involves shunted impedance at the grid to achieve a stable LNA without measuring the S-parameters of transistors at low temperatures.The LNA was measured over the operation band of 2.2-2.3 GHz,which has input and output standing wave ratios below 1.2.The noise figure of the manufactured LNA was about 0.2 dB and the gain was above 22 dB,which indicated that our LNA worked well at 77 K.
基金supported by the National Natural Science Foundation of China(Grant Nos.61176119,61171028,51002081 and 61101018)
文摘The voltage-biased current-voltage （I-V） characteristics of intrinsic Josephson junctions （IJJs）, which are fabricated with misa- ligned high temperature superconducting Tl2Ba2CaCu2O8 （T1-2212） thin film, are investigated experimentally. Three charac- teristic regions in the I-V curve are observed at 47 K. In the low voltage part, the current firstly increases and then decreases slowly with increasing the biased voltage, which is shown as a bump. In the next region, the current slightly increases with in- creasing the biased voltage until a sudden decrease of the current appears. Thereafter, branch structure forms with increasing the voltage on the I-V characteristic. The influence of the self-heating on the I-V characteristics is investigated and the temper- ature dependence of the I-V characteristics is measured to explore these characteristics in detail.
