Flux dynamics in high-temperature superconductors
Flux dynamics in high-temperature superconductors
复制标题
高温超导体中的通量动力学
DOI：
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发表时间：
1993
期刊：
影响因子：
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通讯作者：
M. Nikolo
中科院分区：
文献类型：
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作者：
M. Nikolo
磁通穿透，磁通钉扎和脱钉进行了检查。分析了磁通线热激活跳跃引起的感应电场和电阻率。根据传输或感应电流密度J相对于临界电流密度Jc的相对大小，确定了三种通量状态：（i）J > Jc的热激活通量流（或TAFF）。定义了临界状态及其与磁通蠕动的关系。磁通蠕动，TAFF和磁通流动的电流-电压特性和涡格方面进行了对比。一个相图，在磁场与温度平面，确定了一个典型的高温超导体。定义了涡流流体（TAFF）和涡流固体（通量蠕变）相。研究了超导样品内部的磁通弛豫和磁通分布。的磁通跳跃的特征时间帧进行了对比，在AC场的情况下和频率的影响进行了解释的测量的特征时间。最后，一个基本轮廓的钉扎和已尝试增加钉扎的方法进行了讨论。
Magnetic flux penetration, flux pinning and depinning are examined. The induced electric field and the resistivity due to the thermally activated hopping of the flux lines are analysed. Depending on the relative magnitude of the transport or the induced current density, J, relative to the critical current density, Jc,, three flux regimes are identified: (i) the thermally activated flux flow (or TAFF) for J > Jc. The critical state and its relation to flux creep is defined. The flux creep, TAFF and flux flow are contrasted in terms of the current-voltage characteristics and in terms of the vortex lattice. A phase diagram, in the magnetic field versus temperature plane, is identified for a typical high-temperature superconductor. Vortex fluid (TAFF) and vortex solid (flux creep) phases are defined. Flux relaxation and the flux profile inside a superconducting sample are examined. The characteristic time frame for the flux hopping is contrasted with a characteristic time of measurement in an AC field situation and frequency effects are explained. Finally, a basic outline of pinning and the methods which have been attempted to increase pinning are discussed.