FLUCTUATION EFFECTS IN THE MICROWAVE CONDUCTIVITY OF CUPRATE SUPERCONDUCTORS
FLUCTUATION EFFECTS IN THE MICROWAVE CONDUCTIVITY OF CUPRATE SUPERCONDUCTORS
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铜超导体微波电导率的涨落效应
DOI：
10.1103/physrevb.59.1528
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发表时间：
1999
影响因子：
3.7
通讯作者：
A. Porch
中科院分区：
文献类型：
--
作者：
J. Waldram;D. Broun;D. C. Morgan;R. J. Ormeno;A. Porch
${\mathrm{Bi}}_{2}{\mathrm{Sr}}_{2}{\mathrm{CaCu}}_{2}{\mathrm{O}}_{8+x}$ (Bi2212) 高质量晶体在 14、25 和 36 GHz 下的表面阻抗观察， ${\mathrm{Tl}}_{2}{\mathrm{Ba}}_{2}{\mathrm{CuO}}_{6}$ (Tl2201)，以及报告${\mathrm{YBa}}_{2}({\mathrm{Cu}}_{0.975}{\mathrm{Zn}}_{0.025}{)}_{3}{\mathrm{O}}_{7\ensuremath{-}\ensuremath{\delta}}$ (Y123/Zn)，以及相应的复电导率$\ensuremath{\sigma}={\ensuremath{\sigma}}^{\ensuremath{'}}\ensuremath{-}i{\ensuremath{\sigma}}^{\ensuremath{''}}$ 在 ${T}_{\mathrm{c}}$ 附近的关键区域以及波动很重要的较高温度下进行分析。使用有效介质理论成功分析了关键区域内 ${\ensuremath{\sigma}}^{\ensuremath{'}}$ 中众所周知的尖峰。在较高温度下，Bi2212 和 Y123/Zn 在形式上与 Aslamazov 和 Larkin 的电导率波动处理一致，延伸到高频。然而，Tl2201 显示出在高温下持续的长弛豫时间的额外响应。考虑了对该效应的初步解释，包括其归因于未凝聚双极子的可能性。回顾了波动区域内超电流向正常电流转换的物理原理。
Observations on the surface impedance at 14, 25, and 36 GHz of high quality crystals of ${\mathrm{Bi}}_{2}{\mathrm{Sr}}_{2}{\mathrm{CaCu}}_{2}{\mathrm{O}}_{8+x}$ (Bi2212), ${\mathrm{Tl}}_{2}{\mathrm{Ba}}_{2}{\mathrm{CuO}}_{6}$ (Tl2201), and ${\mathrm{YBa}}_{2}({\mathrm{Cu}}_{0.975}{\mathrm{Zn}}_{0.025}{)}_{3}{\mathrm{O}}_{7\ensuremath{-}\ensuremath{\delta}}$ (Y123/Zn) are reported, and the corresponding complex conductivity $\ensuremath{\sigma}={\ensuremath{\sigma}}^{\ensuremath{'}}\ensuremath{-}i{\ensuremath{\sigma}}^{\ensuremath{''}}$ is analyzed in the critical region near ${T}_{\mathrm{c}}$ and at higher temperatures where fluctuations are important. The well known sharp peak in ${\ensuremath{\sigma}}^{\ensuremath{'}}$ within the critical region is successfully analyzed using effective medium theory. At higher temperatures Bi2212 and Y123/Zn agree in form with the treatment of conductivity fluctuations of Aslamazov and Larkin, extended to high frequency. Tl2201, however, shows an extra response of long relaxation time which persists at high temperatures. Tentative explanations of this effect are considered, including the possibility that it is due to uncondensed bipolarons. The physics of conversion of supercurrent to normal current within fluctuating regions is reviewed.