Theory of percolative conduction in polycrystalline high-temperature superconductors
Theory of percolative conduction in polycrystalline high-temperature superconductors
复制标题
多晶高温超导体的渗流传导理论
DOI：
10.1103/physrevb.61.4206
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发表时间：
1998
期刊：
影响因子：
--
通讯作者：
R. Joynt
中科院分区：
文献类型：
--
作者：
R. Haslinger;R. Joynt
具有较高临界电流的大块多晶高{T}_{c}$超导体的传导已被证明是渗透的。这种现象是由于晶界处的薄弱环节造成的。这些薄弱环节是需要高电流密度的技术应用的主要限制因素。我们建立了一个可以简化为非线性电阻网络的这些材料的模型。该模型采用解析近似法和一种新的数值方法求解。数值技术是变分的，这使得它能够解决各种各样的非线性问题。结果表明，样品中临界电流分布的存在并没有消除有关单个边界耗散电性质的所有信息。这意味着可以在微观水平上的$I\ensuremath{-}V$特征与宏观电学性质之间建立明确的联系。
Conduction in bulk polycrystalline high-${T}_{c}$ superconductors with relatively high critical currents has been shown to be percolative. This phenomenon is due to weak links at grain boundaries. These weak links are the major limiting factor for technological applications that require high-current densities. We formulate a model of these materials that can be reduced to a nonlinear resistor network. The model is solved by analytical approximations and a new numerical technique. The numerical technique is variational, which makes it capable of solving a wide variety of nonlinear problems. The results show that the presence of a distribution of critical currents in the sample does not erase all information about the dissipative electrical properties of individual boundaries. This means that an unambiguous connection can be made between the $I\ensuremath{-}V$ characteristics at the microscopic level and the macroscopic electrical properties.