AI 中文总结
研究利用NbN微波谐振器，探究无序对超导响应的影响。通过实验发现最薄薄膜有反常超导响应，随厚度增加向传统转变，揭示纳米晶孪晶域结构是关键因素，确定超流刚度与配对能量比值Theta(0)/Tc是控制边界的参数。
AI 中文摘要
无序是实现超导超薄膜高动电感的有效途径，可实现紧凑的高阻抗量子电路。但此功能是以降低相刚度和潜在的反常电动力学为代价的。本文利用厚度低至2.8nm、面动电感高达300pH/square的NbN微波谐振器，探究这种权衡如何重塑超导响应。在最薄的薄膜中，输运显示出 Berezinskii-Kosterlitz-Thouless 转变的特征，而微波响应揭示了超流刚度在低温下明显的幂律抑制，这与 Mattis-Bardeen 理论不一致。随着厚度增加，这种反常状态逐渐受到抑制，标志着向传统的能隙主导电动力学的连续转变。横截面透射电子显微镜揭示了纳米晶孪晶域结构，表明取向微结构无序是观察到的响应中的关键因素。总体而言，这种转变由超流刚度与配对能量的比值Theta(0)/Tc 控制，确定该比值是控制无序纳米薄膜中相涨落主导和能隙主导超导电动力学之间边界的参数。
英文摘要
Disorder is a powerful route to high kinetic inductance in superconducting ultrathin films, enabling compact high-impedance quantum circuits. This functionality, however, comes at the cost of reduced phase rigidity and potentially anomalous electrodynamics. Here, we use NbN microwave resonators with thicknesses down to 2.8 nm and sheet kinetic inductance up to 300 pH per square to probe how this trade-off reshapes the superconducting response. In the thinnest films, transport shows signatures of a Berezinskii-Kosterlitz-Thouless transition, while the microwave response reveals a pronounced low-temperature power-law suppression of the superfluid stiffness, inconsistent with Mattis-Bardeen theory. With increasing thickness, this anomalous regime is progressively suppressed, marking a continuous crossover toward conventional, gap-dominated electrodynamics. Cross-sectional transmission electron microscopy reveals a nanocrystalline twin-domain structure, pointing to oriented microstructural disorder as a crucial factor in the observed response. Overall, the crossover is governed by the ratio of superfluid stiffness to pairing energy, Theta(0)/Tc, identifying this ratio as a parameter governing the boundary between phase-fluctuation-dominated and gap-dominated superconducting electrodynamics in disordered nanofilms.
