Power-law temperature dependence of the electrodynamic properties in oriented YBa2Cu3O7−δ and Y2Ba4Cu8O16−δ films

Abstract

Measurements of the temperature dependence of the surface resistance $R_s$ and of the surface reactance $X_s$ at 148 GHz are reported for $\mathrm{Y}{\mathrm{Ba}}_2{\mathrm{Cu}}_3{\mathrm{O}}_{7-\delta }$ and ${\mathrm{Y}}_2{\mathrm{Ba}}_4{\mathrm{Cu}}_8{\mathrm{O}}_{16-\delta }$ superconducting films with the $c$ axis oriented perpendicular to the film's substrate. For low temperatures ($T<\mathrm{}\frac{T_c}{2}$) we find $X_s\mathrm{}\left(T\right)-X_s\mathrm{}\left(0\right)=B{T}^2$ and $R_s\mathrm{}\left(T\right)-R_s\mathrm{}\left(0\right)=AT$. The implications of these results are discussed.