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arXiv 1609.06397cond-mat.supr-con
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薄膜超导体的普适自场临界电流

Universal self-field critical current for thin-film superconductors

Evgeny F. Talantsev, Jeffery L. Tallon

摘要:

对于任何实际的超导体,临界电流密度$J_\textrm{c}$的大小是至关重要的。它设置导体中电流的上限。通常,$J_\textrm{c}$随着外部磁场的增加而迅速下降,但即使在零外部磁场中,导体中流动的电流也会产生限制$J_\textrm{c}$的自场。在这里,我们显示的薄膜厚度小于伦敦的穿透深度,$λ$,这个限制$J_\textrm{c}$采用了所有超导体的普遍价值-金属,氧化物,铜酸盐,磷属元素化物,硼碳化物和重费米子。对于I型超导体,它是$H_{\textrm{c}}/λ$,其中$H_\textrm{c}$是热力学临界场。但令人惊讶的是,对于II型超导体,我们发现自场$J_\textrm{c}$是$H_{\textrm{c}1}/λ$,其中$H_{\textrm{c}1}$是较低的临界场。因此,从根本上确定了$J_\textrm{c}$,这提供了一种简单的方法来提取$λ(T)$的绝对值,并从其温度依赖性中提取超导能隙的对称性和大小。

英文摘要:

For any practical superconductor the magnitude of the critical current density, $J_\textrm{c}$, is crucially important. It sets the upper limit for current in the conductor. Usually $J_\textrm{c}$ falls rapidly with increasing external magnetic field but even in zero external field the current flowing in the conductor generates a self-field which limits $J_\textrm{c}$. Here we show for thin films of thickness less than the London penetration depth, $λ$, this limiting $J_\textrm{c}$ adopts a universal value for all superconductors - metals, oxides, cuprates, pnictides, borocarbides and heavy Fermions. For type I superconductors, it is $H_{\textrm{c}}/λ$ where $H_\textrm{c}$ is the thermodynamic critical field. But surprisingly for type II superconductors we find the self-field $J_\textrm{c}$ is $H_{\textrm{c}1}/λ$ where $H_{\textrm{c}1}$ is the lower critical field. $J_\textrm{c}$ is thus fundamentally determined and this provides a simple means to extract absolute values of $λ(T)$ and, from its temperature dependence, the symmetry and magnitude of the superconducting gap.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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