Dynamic Scaling and Two-Dimensional High-Tc Superconductors
Dynamic Scaling and Two-Dimensional High-Tc Superconductors
复制标题
动态缩放和二维高温超导体
DOI：
10.1103/physrevb.67.174517
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发表时间：
2003
影响因子：
3.7
通讯作者：
R. Newrock
中科院分区：
文献类型：
--
作者：
D. R. Strachan;C. Lobb;R. Newrock
二维超导体的临界行为一直存在争议，特别是对于高Tc超导体。传统的观点认为，只要有限尺寸效应不掩盖这种转变，就会发生Kosterlitz-Schless-Berezinskii转变。然而，最近有人提出，实际上发生了一个不同的过渡，它结合了Fisher，Fisher和Huse的动态标度理论和Kosterlitz-Berezinskii过渡。普遍感兴趣的是，这种修改的过渡显然有一个普遍的动态临界指数。有些人反驳说，这种明显的普遍行为是植根于一个新提出的有限尺寸标度理论;一个也结合了标度和传统的二维理论。为了研究这些问题，我们研究了12埃厚的YBa 2Cu 3 O 7 - δ薄膜的直流电压-电流数据。我们发现，新提出的标度理论具有内在的灵活性，是相关的实验分析。特别是，数据根据任意定义的临界温度（0至19.5 K之间）的修改过渡进行缩放，并且成功缩放崩溃的温度范围与测量的灵敏度直接相关。这意味着，表观普适指数是由于内在的灵活性，而不是一些真实的物理性质。为了解决这种内在的灵活性，我们提出了一个标准，这将提供确凿的证据，在二维超导体的相变。最后，我们回顾结果，看看是否满足我们的标准。
There has been ongoing debate over the critical behavior of two-dimensional superconductors; in particular for high T c superconductors. The conventional view is that a Kosterlitz-Thouless-Berezinskii transition occurs aslong as finite size effects do not obscure the transition. However, there have been recent suggestions that a different transition actually occurs which incorporates aspects of both the dynamic scaling theory of Fisher, Fisher, and Huse and the Kosterlitz-Thouless-Berezinskii transition. Of general interest is that this modified transition apparently has a universal dynamic critical exponent. Some have countered that this apparent universal behavior is rooted in a newly proposed finite-size scaling theory; one that also incorporates scaling and conventional two-dimensional theory. To investigate these issues we study dc voltage versus current data of a 12-A-thick YBa 2 Cu 3 O 7 - δ film. We find that the newly proposed scaling theories have intrinsic flexibility that is relevant to the analysis of the experiments. In particular, the data scale according to the modified transition for arbitrarily defined critical temperatures between 0 and 19.5 K, and the temperature range of a successful scaling collapse is related directly to the sensitivity of the measurement. This implies that the apparent universal exponent is due to the intrinsic flexibility rather than some real physical property. To address this intrinsic flexibility, we propose a criterion which would give conclusive evidence for phase transitions in two-dimensional superconductors. We conclude by reviewing results to see if our criterion is satisfied.