Anisotropy and field dependence of critical current density in YBa2Cu3O7−δ epitaxial thin film

1997 ◽  
Vol 81 (11) ◽  
pp. 7392-7395 ◽  
Author(s):  
X. W. Cao ◽  
Z. H. Wang ◽  
J. Fang ◽  
X. J. Xu ◽  
K. B. Li
2000 ◽  
Vol 53 (6) ◽  
pp. 821
Author(s):  
Lei Shan ◽  
Sahr Augustine Aruna ◽  
Xiao-Nong Xu ◽  
Zhi-He Wang ◽  
Xin Jin

The current–voltage characteristics have been measured on aYBa2Cu3O7-δ epitaxial thin film. Using a material power law, we determine the temperature and field dependencies of the characteristic pinning potential UJand the real critical current density Jc at different fields and temperatures. It is shown that Jc is completely different from the conventional critical current density JE, which is determined by the electronic-field criterion. Thus, the time-honoured electronic-field criterion is no longer reasonable for high-Tc superconductors. By further investigation of the results of Jc and UJ, we are able to present a physical picture of the transformation of the pinning potential well with increasing temperature and hence determine the transition point from vortex-glass phase to vortex-liquid phase.


Author(s):  
P. Lu ◽  
W. Huang ◽  
C.S. Chern ◽  
Y.Q. Li ◽  
J. Zhao ◽  
...  

The YBa2Cu3O7-x thin films formed by metalorganic chemical vapor deposition(MOCVD) have been reported to have excellent superconducting properties including a sharp zero resistance transition temperature (Tc) of 89 K and a high critical current density of 2.3x106 A/cm2 or higher. The origin of the high critical current in the thin film compared to bulk materials is attributed to its structural properties such as orientation, grain boundaries and defects on the scale of the coherent length. In this report, we present microstructural aspects of the thin films deposited on the (100) LaAlO3 substrate, which process the highest critical current density.Details of the thin film growth process have been reported elsewhere. The thin films were examined in both planar and cross-section view by electron microscopy. TEM sample preparation was carried out using conventional grinding, dimpling and ion milling techniques. Special care was taken to avoid exposure of the thin films to water during the preparation processes.


2012 ◽  
Vol 1434 ◽  
Author(s):  
Kohei Higashikawa ◽  
Kei Shiohara ◽  
Masayoshi Inoue ◽  
Takanobu Kiss ◽  
Masateru Yoshizumi ◽  
...  

ABSTRACTTo enhance a global critical current in a superconductor, it is indispensable to understand current limiting factors and their influence on such a critical current. From this point of view, we have investigated in-plane distribution of local critical current density and its electric field criterion in a thin-film superconductor by using scanning-Hall probe microscopy. In a remanent state, after the application of sufficiently high magnetic field to a sample, current flows at critical current density according to the critical state model. Such distribution of current density was estimated from that of measured magnetic field using the Biot-Savart law. Furthermore, the corresponding electric field criterion was evaluated from the relaxation of such remanent magnetic field by considering Faraday’s law. This means that we could estimate in-plane distribution of local critical current density as a function of electric field criterion in a nondestructive manner. This characterization method would be very helpful for finding current limiting factors in a thin-film superconductor and their influence on its global current density versus electric field properties which would usually be obtained by four-probe method.


1991 ◽  
Vol 30 (Part 1, No. 11A) ◽  
pp. 2747-2750 ◽  
Author(s):  
Michiya Okada ◽  
Toshihide Nabatame ◽  
Toyotaka Yuasa ◽  
Katsuzo Aihara ◽  
Masahiro Seido ◽  
...  

Pramana ◽  
1988 ◽  
Vol 31 (4) ◽  
pp. L343-L346 ◽  
Author(s):  
P K Mishra ◽  
G Ravi Kumar ◽  
P Chaddah ◽  
B A Dasannacharya ◽  
M K Malik

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