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arXiv 2304.09360cond-mat.supr-concond-mat.mtrl-sci
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超导体-超导体双层结构中电流抑制的证据

Evidence for current suppression in superconductor-superconductor bilayers

Md Asaduzzaman, Ryan M. L. McFadden, Anne-Marie Valente-Feliciano, David R. Beverstock, Andreas Suter, Zaher Salman, Thomas Prokscha, Tobias Junginger

AI总结:

本研究通过低能μ子自旋转动测量证实超导体-超导体双层结构中表面电流被抑制,并估算出最佳厚度约为261 nm,为优化SRF腔性能提供依据。

摘要:

超导射频(SRF)腔是许多粒子加速器中的关键部件,必须在迈斯纳态下运行,以避免磁通涡旋引起的强耗散。对于无缺陷的超导体,可达到的最大运行磁场由超加热场 $B_{\mathrm{sh}}$ 决定,该场直接依赖于表面电流。在由不同超导体组成的异质结构中,每层中的电流不仅取决于单个材料的性质,还通过界面处的边界条件取决于相邻层的电磁响应。本文通过使用低能μ子自旋转动(LE-$\mu$SR)对迈斯纳屏蔽轮廓进行深度分辨测量,研究了三种典型的双层结构 [ $\mathrm{Nb_{1-x}Ti_xN}$(50 nm)/Nb、$\mathrm{Nb_{1-x}Ti_xN}$(80 nm)/Nb 和 $\mathrm{Nb_{1-x}Ti_xN}$(160 nm)/Nb ]。基于伦敦理论(具有适当的边界和连续性条件)的模型拟合发现,薄 $\mathrm{Nb_{1-x}Ti_xN}$ 层的磁穿透深度为 $λ_\mathrm{Nb_{1-x}Ti_xN} =$ 182.5(31) nm,与块体合金的文献值吻合良好。利用测得的 $λ_\mathrm{Nb_{1-x}Ti_xN}$,估算出超导体-超导体(SS)双层结构的最大无涡旋场 $B_{\mathrm{max}}$ 为 610(40) mT。$\mathrm{Nb_{1-x}Ti_xN}$ 层中表面电流的强烈抑制表明最佳厚度约为 $\sim 1.4 λ_{\mathrm{Nb_{1-x}Ti_xN}} =$ 261(14) nm。

英文摘要:

Superconducting radio frequency (SRF) cavities, which are critical components in many particle accelerators, need to be operated in the Meissner state to avoid strong dissipation from magnetic vortices. For a defect-free superconductor, the maximum attainable magnetic field for operation is set by the superheating field, $B_{\mathrm{sh}}$, which directly depends on the surface current. In heterostructures composed of different superconductors, the current in each layer depends not only on the properties of the individual material, but also on the electromagnetic response of the adjacent layers through boundary conditions at the interfaces. Three prototypical bilayers [$\mathrm{Nb_{1-x}Ti_xN}$(50 nm)/Nb, $\mathrm{Nb_{1-x}Ti_xN}$(80 nm)/Nb, and $\mathrm{Nb_{1-x}Ti_xN}$(160 nm)/Nb] are investigated here by depth-resolved measurements of their Meissner screening profiles using low-energy muon spin rotation (LE-$μ$SR). From fits to a model based on London theory (with appropriate boundary and continuity conditions), a magnetic penetration depth for the thin $\mathrm{Nb_{1-x}Ti_xN}$ layers of $λ_\mathrm{Nb_{1-x}Ti_xN} =$ 182.5(31) nm is found, in good agreement with literature values for the bulk alloy. Using the measured $λ_\mathrm{Nb_{1-x}Ti_xN}$, the maximum vortex-free field, $B_{\mathrm{max}}$, of the superconductor-superconductor (SS) bilayer structure was estimated to be 610(40) mT. The strong suppression of the surface current in the $\mathrm{Nb_{1-x}Ti_xN}$ layer suggests an optimal thickness of $\sim 1.4 λ_{\mathrm{Nb_{1-x}Ti_xN}} =$ 261(14) nm.

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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