Tl-based superconducting devices have been drawn much attention for their high transition temperature(T_c), which allow the high temperature superconductors(HTS) devices to operate at temperature near 100 K. The reali...Tl-based superconducting devices have been drawn much attention for their high transition temperature(T_c), which allow the high temperature superconductors(HTS) devices to operate at temperature near 100 K. The realization of Tlbased devices will promote the research and application of HTS devices. In this work, we present transport properties of Tl_(2) Ba_(2) CaCu_(2) O_(8)(Tl-2212) microbridges across a low-angle step on LaAlO_(3)(LAO) substrate. We experimentally demonstrate intrinsic Josephson effects(IJEs) in Tl-2212 films by tailoring the geometry, i.e., reducing the width of the microbridges. In the case of a 1 μm width microbridge, in addition to the observation of voltage branches and remarkable hysteresis on the current–voltage(I–V) characteristics, the temperature dependence of differential resistance shows a finite resistance above 60 K when the bias current is below the critical current. For comparison, the wider microbridges are also investigated, exhibiting a highly critical current but do not showing obvious IJEs.展开更多
TlBa_2 Ca_2 Cu_3 O_9(Tl-1223) films have promising applications due to their high critical temperature and strong magnetic flux pinning. Nevertheless, the preparation of pure phase Tl-1223 film is still a challenge. W...TlBa_2 Ca_2 Cu_3 O_9(Tl-1223) films have promising applications due to their high critical temperature and strong magnetic flux pinning. Nevertheless, the preparation of pure phase Tl-1223 film is still a challenge. We successfully fabricate Tl-1223 thin films on LaAlO_3(001) substrates using dc magnetic sputtering and a post annealing two-step method in argon atmosphere. The crystallization temperature of Tl-1223 films in argon is reduced by 100℃ compared to that in oxygen. This greatly reduces the volatilization of Tl and improves the surface morphology of films. The lower annealing temperature can effectively improve the repeatability of the Tl-1223 film preparation. In addition, pure Tl-1223 phase can be obtained in a broad temperature zone,from 790℃ to 830℃. In our study, the films show homogenous and dense surface morphology using the presented method. The best critical temperature of Tl-1223 films is characterized to be 110 K, and the critical current J_c(77 K, 0 T) is up to 2.13 × 106 A/cm^2.展开更多
We report the circuit simulations and experiments of millimeter-wave radiation from a high temperature superconducting(HTS) bicrystal Josephson junction(BJJ) array. To study the effects of junction characteristic para...We report the circuit simulations and experiments of millimeter-wave radiation from a high temperature superconducting(HTS) bicrystal Josephson junction(BJJ) array. To study the effects of junction characteristic parameters on radiation properties, new radiation circuit models are proposed in this paper. The series resistively and capacitively shunted junction(RCSJ) models are packaged into a Josephson junction array(JJA) model in the simulation. The current-voltage characteristics(IVCs) curve and radiation peaks are simulated and analyzed by circuit models, which are also observed from the experiment at liquid nitrogen temperature. The experimental radiation linewidth and power are in good agreement with simulated results. The presented circuit models clearly demonstrate that the inconsistency of the JJA will cause a broad linewidth and a low detected power. The junction radiation properties are also investigated at the optimal situation by circuit simulation. The results further confirm that the consistent JJA characteristic parameters can successfully narrow the radiation linewidth and increase the power of junction radiation.展开更多
In Fig.2 of the article,[1]the figure caption should be“Rocking curve of the(006)peak of the Tl-1223 thin film”instead of“Rocking curve of the(003)peak of the Tl-1223 thin film”.The corresponding description of th...In Fig.2 of the article,[1]the figure caption should be“Rocking curve of the(006)peak of the Tl-1223 thin film”instead of“Rocking curve of the(003)peak of the Tl-1223 thin film”.The corresponding description of this figure should be“As shown in Fig.2,the full width at half maximum(FWHM)of the Tl-1223(006)reflection peak is only 0.58∘,which shows that the film possesses a good crystalline structure”,instead of“As shown in Fig.2,the FWHM of the Tl-1223(003)reflection peak is only 0.58∘,which shows that the film possesses a good crystalline structure”.展开更多
文摘Tl-based superconducting devices have been drawn much attention for their high transition temperature(T_c), which allow the high temperature superconductors(HTS) devices to operate at temperature near 100 K. The realization of Tlbased devices will promote the research and application of HTS devices. In this work, we present transport properties of Tl_(2) Ba_(2) CaCu_(2) O_(8)(Tl-2212) microbridges across a low-angle step on LaAlO_(3)(LAO) substrate. We experimentally demonstrate intrinsic Josephson effects(IJEs) in Tl-2212 films by tailoring the geometry, i.e., reducing the width of the microbridges. In the case of a 1 μm width microbridge, in addition to the observation of voltage branches and remarkable hysteresis on the current–voltage(I–V) characteristics, the temperature dependence of differential resistance shows a finite resistance above 60 K when the bias current is below the critical current. For comparison, the wider microbridges are also investigated, exhibiting a highly critical current but do not showing obvious IJEs.
基金Supported by the National Natural Science Foundation of China under Grant No 51002081the Fundamental Research Funds for the Central Universities of Chinathe Research Program of Application Foundation and Advanced Technology of Tianjin under Grant No 15JCQNJC01300
文摘TlBa_2 Ca_2 Cu_3 O_9(Tl-1223) films have promising applications due to their high critical temperature and strong magnetic flux pinning. Nevertheless, the preparation of pure phase Tl-1223 film is still a challenge. We successfully fabricate Tl-1223 thin films on LaAlO_3(001) substrates using dc magnetic sputtering and a post annealing two-step method in argon atmosphere. The crystallization temperature of Tl-1223 films in argon is reduced by 100℃ compared to that in oxygen. This greatly reduces the volatilization of Tl and improves the surface morphology of films. The lower annealing temperature can effectively improve the repeatability of the Tl-1223 film preparation. In addition, pure Tl-1223 phase can be obtained in a broad temperature zone,from 790℃ to 830℃. In our study, the films show homogenous and dense surface morphology using the presented method. The best critical temperature of Tl-1223 films is characterized to be 110 K, and the critical current J_c(77 K, 0 T) is up to 2.13 × 106 A/cm^2.
基金Project supported by the National Natural Science Foundation of China(Grant No.51002081)the Fundamental Research Funds for the Central Universities,China+1 种基金the China Manned Space Advance Research Program,China(Grant No.030201)the Research Program of Application Foundation and Advanced Technology of Tianjin,China(Grant No.15JCQNJC01300)
文摘We report the circuit simulations and experiments of millimeter-wave radiation from a high temperature superconducting(HTS) bicrystal Josephson junction(BJJ) array. To study the effects of junction characteristic parameters on radiation properties, new radiation circuit models are proposed in this paper. The series resistively and capacitively shunted junction(RCSJ) models are packaged into a Josephson junction array(JJA) model in the simulation. The current-voltage characteristics(IVCs) curve and radiation peaks are simulated and analyzed by circuit models, which are also observed from the experiment at liquid nitrogen temperature. The experimental radiation linewidth and power are in good agreement with simulated results. The presented circuit models clearly demonstrate that the inconsistency of the JJA will cause a broad linewidth and a low detected power. The junction radiation properties are also investigated at the optimal situation by circuit simulation. The results further confirm that the consistent JJA characteristic parameters can successfully narrow the radiation linewidth and increase the power of junction radiation.
基金Supported by the National Natural Science Foundation of China(Grant No.51002081)the Fundamental Research Funds for the Central Universities of Chinathe Research Program of Application Foundation and Advanced Technology of Tianjin(Grant No.15JCQNJC01300).
文摘In Fig.2 of the article,[1]the figure caption should be“Rocking curve of the(006)peak of the Tl-1223 thin film”instead of“Rocking curve of the(003)peak of the Tl-1223 thin film”.The corresponding description of this figure should be“As shown in Fig.2,the full width at half maximum(FWHM)of the Tl-1223(006)reflection peak is only 0.58∘,which shows that the film possesses a good crystalline structure”,instead of“As shown in Fig.2,the FWHM of the Tl-1223(003)reflection peak is only 0.58∘,which shows that the film possesses a good crystalline structure”.
