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New features in the microwave response of YBCO crystals: Evidence for a multi-component order parameter

H. Srikanth·Balam A. Willemsen·T. Jacobs·S. Sridhar·A. Erb·E. Walker·R. Flukiger
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Abstract

New features are reported in precision measurements of the complex microwave conductivity of high quality $YBa_{2}Cu_{3}O_{6.95}$ crystals grown in $BaZrO_{3}$ crucibles. A third peak in the normal conductivity, $σ_{1}(T)$, at around $80K$, and enhanced pair conductivity $σ_{2}(T)$ below $\sim 65K$ are observed. The data are inconsistent with a single order parameter, and instead are indicative of multi-component superconductivity. Overall, these results point to the presence of multiple pairing interactions in $YBa_{2}Cu_{3}O_{6.95}$ and also provide a natural explanation to account for the low temperature $35K$ conductivity peak observed in all $YBa_{2}Cu_{3}O_{6.95}$ crystals.

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H. Srikanth, Balam A. Willemsen, T. Jacobs, S. Sridhar, A. Erb, E. Walker, R. Flukiger. 1997-04-24. New features in the microwave response of YBCO crystals: Evidence for a multi-component order parameter. https://doi.org/10.1103/physrevb.55.r14733

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