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arXiv 1012.1104cond-mat.supr-con
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无序二维超导体的涨落

Fluctuoscopy of Disordered Two-Dimensional Superconductors

A. Glatz, A. A. Varlamov, V. M. Vinokur

摘要:

我们修正了长期研究的问题的波动电导率(FC)在无序的二维超导体放置在一个垂直的磁场中,最终推导出完整的解决方案的温度-磁场相图。所得到的表达式允许进行直接(数值)计算的FC表面$δσ_{xx}^{(\mathrm{tot})}(T,H)$,并得到渐近表达式在其所有的定性不同的域。该表面在低温下变得特别重要,其中它是具有$% δσ_{xx}^{(\mathrm{tot})}(T,H)<0$的槽形。在这个区域,接近量子相变,$δσ_{xx}^{(\mathrm{tot})}(T,H=\mathrm{const})$是非单调的,与实验结果一致。我们重新分析和比较几个实验测量。在此基础上,我们得到了超导涨落在$H_{\mathrm{c2}}(0) $附近和T=0时的定性图象,其中涨落Cooper对以回旋频率$ω_{c}\simΔ_{\mathrm{BCS}}^{-1}$和Larmor半径$\sim ξ_{\mathrm{BCS}}$旋转,形成了某种具有长相干长度$ξ_{\mathrm{QF}}\ggξ_{\mathrm{BCS}}$和慢弛豫的量子液体($τ_{\mathrm{QF}}\gg\hbarΔ_{\mathrm{BCS}}^{-1}$).

英文摘要:

We revise the long studied problem of fluctuation conductivity (FC) in disordered two-dimensional superconductors placed in a perpendicular magnetic field by finally deriving the complete solution in the temperature-magnetic field phase diagram. The obtained expressions allow both to perform straightforward (numerical) calculation of the FC surface $δσ_{xx}^{(\mathrm{tot})}(T,H)$ and to get asymptotic expressions in all its qualitatively different domains. This surface becomes in particular non-trivial at low temperatures, where it is trough-shaped with $% δσ_{xx}^{(\mathrm{tot})}(T,H)<0$. In this region, close to the quantum phase transition, $δσ_{xx}^{(\mathrm{tot})}(T,H=\mathrm{const})$ is non-monotonic, in agreement with experimental findings. We reanalyzed and present comparisons to several experimental measurements. Based on our results we derive a qualitative picture of superconducting fluctuations close to $H_{\mathrm{c2}}(0) $ and T=0 where fluctuation Cooper pairs rotate with cyclotron frequency $ω_{c}\simΔ_{\mathrm{BCS}}^{-1}$ and Larmor radius $\sim ξ_{\mathrm{BCS}}$, forming some kind of quantum liquid with long coherence length $ξ_{\mathrm{QF}}\ggξ_{\mathrm{BCS}}$ and slow relaxation ($τ_{\mathrm{QF}}\gg\hbarΔ_{\mathrm{BCS}}^{-1}$).

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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