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Offset criterion for determining superconductor critical current

 

作者: J. W. Ekin,  

 

期刊: Applied Physics Letters  (AIP Available online 1989)
卷期: Volume 55, issue 9  

页码: 905-907

 

ISSN:0003-6951

 

年代: 1989

 

DOI:10.1063/1.102259

 

出版商: AIP

 

数据来源: AIP

 

摘要:

Critical‐current criteria based on electric field or resistivity can present a number of problems in defining critical current, especially for highTcsuperconductors in the vicinity of the critical temperature or upper critical field. The resulting critical‐current densityJccan be quite arbitrary, since it depends strongly on criterion level at high fields and temperatures. TheseJcdefinitions also create problems in distinguishing between superconductors and high‐conductivity normal metals such as copper. They can also biasJcdata when superconductors are compared that have different values of normal‐state resistivity. To minimize these problems, an intrinsicJccriterion is proposed, which effectively separates superconducting and normal‐state properties. Based on the long‐standing concept of a flux‐flow resistivity,Jcis defined as the current where the tangent to theE‐Jcurve at a given electric field level extrapolates to zero electric field. This determines an offsetJcthat minimizes the above problems. The criterion is particularly useful nearTcor near the effective upper critical field where theE‐Jcharacteristic starts to approach ohmic behavior.

 

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