Low-field microwave absorption in polycrystalline YBa₂Cu₃O₇₋ₓ was measured as a function of dc current applied through the sample at various temperatures below Tc. The peak-to-peak value of the magnetically modulated microwave absorption (MMMA) signal increases with dc current at a fixed temperature. Above a threshold value of the current, the absorption signal level rapidly drops to zero, indicating quenching of superconductivity. If this critical current is plotted as a function of temperature, the results can be explained on the basis of the flux creep model. The MMMA signal obeys a scaling rule as predicted by the flux creep model. We conclude that flux creep limits the critical current density in these materials; also, this presents a new way of measuring critical current densities while using only a two-contact method. It gives some insight into the relationship between microwave properties and dc transport phenomena in these superconductors.


Originally published in Journal of Applied Physics 67, 5076 (1990). DOI:10.1063/1.344675 (http://dx.doi.org/10.1063/1.344675).


magnetically modulated microwave absorption, dc transport current, polycrystalline YBCO, YBa₂Cu₃O₇₋ₓ, MMMA, absorption signal level, flux creep model

Subject Categories

Superconductors, Superconductivity


Electromagnetics and photonics


American Institute of Physics

Publication Date


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Copyright 1990 American Institute of Physics.

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American Institute of Physics

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