统一输运与磁化率分析薄BSCCO薄膜：从局域配对到全局相位相干
Unified Transport and Susceptibility Analysis of a Thin BSCCO Film: From Local Pairing to Global Phase Coherence
- Indian Institute of Science（印度科学学院）
机构由 AI 辅助整理，请以论文原文为准。
AI总结：
通过输运与交流磁化率测量，结合扩展的Choy--Stoneham模型，揭示薄BSCCO薄膜中超导转变从局域配对逐步发展到全局相位相干的渐进过程。
AI中文摘要：
薄的高温超导薄膜中的超导转变可能因无序、空间不均匀性和相位涨落而显著展宽。本文通过电输运和交流磁化率测量，研究了厚度为30纳米的溅射生长Bi$_2$Sr$_2$CaCu$_2$O$_{8+\delta}$（BSCCO）薄膜中的超导转变。电阻转变分别使用局域$T_c$值的高斯分布和Ambegaokar--Halperin模型进行检验，这两个模型分别描述了超导电性的空间变化和热激活相位动力学。为了将输运响应与磁响应联系起来，我们扩展了Choy--Stoneham磁化率模型，引入了从输运测量中提取的超导分数，以及一个表示超导区域间约瑟夫森耦合逐渐发展的温度依赖连接因子。结果识别出对应于局域超导起始、超导分数扩展、磁屏蔽发展和全局相位相干建立的不同温度区间。因此，转变从局域超导区域逐步演化为连通且相位相干的状态。该分析为不均匀超导薄膜中空间不均匀性、耗散相位动力学和磁屏蔽之间的关联提供了一个统一框架。
英文摘要：
The superconducting transition in thin high-$T_c$ films can be significantly broadened by disorder, spatial inhomogeneity, and phase fluctuations. Here, we study the transition in a 30-nm-thick sputter-grown Bi$_2$Sr$_2$CaCu$_2$O$_{8+δ}$ (BSCCO) film through electrical-transport and ac-susceptibility measurements. The resistive transition is examined using a Gaussian distribution of local $T_c$ values and the Ambegaokar--Halperin model, describing spatial variations in superconductivity and thermally activated phase dynamics, respectively. To relate the transport and magnetic responses, we extend the Choy--Stoneham susceptibility model by introducing the superconducting fraction extracted from transport and a temperature-dependent connectivity factor representing the gradual development of Josephson coupling among superconducting regions. The results identify separate temperature regimes corresponding to the onset of local superconductivity, expansion of the superconducting fraction, development of magnetic screening, and establishment of global phase coherence. The transition therefore proceeds progressively, from locally superconducting regions to a connected, phase-coherent state. This analysis provides a common framework for relating spatial inhomogeneity, dissipative phase dynamics, and magnetic screening in inhomogeneous superconducting films.
