Phenomenological Description of Temperature and Frequency Dependence of Surface Resistance of High-T_c Superconductors by Improved Three-Fluid Model

摘要

A calculation method by the improved three-fluid model is shown to describe phenomenologically temperature and frequency dependence of surface resistance R_s for high-T_c superconductors. It is verified that this model is useful to describe temperature dependence of R_s for such high-T_c superconducting films as Y-Ba-Cu-O (YBCO), Eu-Ba-Cu-O, and Tl-Ba-Ca-Cu-O films. For the frequency dependence of R_s of a YBCO bulk, furthermore, the measured results which have not depended on f~2 in the frequency range 10-25 GHz, can be described successfully by this model. Finally, a figure of merit is proposed to evaluate material quality for high-T_c superconductors from the values of electron densities and momentum relaxation time determined by the present model.