The in-plane resistance of two single crystals of $\mathrm{Y}{\mathrm{Ba}}_2{\left({\mathrm{Cu}}_{1-0.01x}{\mathrm{Zn}}_{0.01x}\right)}_3{\mathrm{O}}_{7-\delta }$, $x=1\mathrm{} \mathrm{and} 3.5$, was measured in magnetic fields up to 12 T parallel to the $c$ axis at temperatures $\epsilon =\ln \left(\frac{T}{T_c}\right)$ up to about $\frac{1}{3}$. The coherence lengths and the phase-breaking scattering time ${\tau }_{\phi }$ were determined. ${\xi }_{\mathrm{ab}}$ and ${\xi }_c$ were both found to decrease with Zn doping, with a slow increase of the anisotropy ratio $\frac{{\xi }_{\mathrm{ab}}}{{\xi }_c}$. The phase-breaking scattering rate $\frac{1}{{\tau }_{\phi }}$ increases strongly with increasing Zn concentration, indicating that Zn causes pair breaking in $\mathrm{Y}{\mathrm{Ba}}_2{\mathrm{Cu}}_3{\mathrm{O}}_{7-\delta }$.

• Received 13 July 1995

DOI:https://doi.org/10.1103/PhysRevB.53.R3003