Systematic behavior of the in-plane penetration depth ind-wave cuprates

We report the temperature $\mathrm{}\left(T\right)\mathrm{}$ and oxygen concentration dependences of the penetration depth of grain-aligned ${\mathrm{YBa}}_2{\mathrm{Cu}}_3{\mathrm{O}}_{7\mathrm{-}\mathrm{\delta }}$ with $\delta =0.0,$ 0.3, and 0.43. The values of the in-plane ${\lambda }_{\mathrm{ab}}\mathrm{}\left(0\right)\mathrm{}$ and out-of-plane ${\lambda }_c\mathrm{}\left(0\right)\mathrm{}$ penetration depths, the low-temperature linear term in ${\lambda }_{\mathrm{ab}}\mathrm{}\left(T\right),$ and the ratio $\left[{\lambda }_c\mathrm{}\right(0)/{\lambda }_{\mathrm{ab}}\mathrm{}(0\left)\mathrm{}\right]$ were found to increase with increasing δ. The systematic changes of the linear term in ${\lambda }_{\mathrm{ab}}\mathrm{}\left(T\right)\mathrm{}$ with $T_c$ found here and in recent work on ${\mathrm{HgBa}}_2{\mathrm{Ca}}_{n-1}{\mathrm{Cu}}_n{\mathrm{O}}_{2n+2+\delta }$ ($n=1\mathrm{}$ and 3) are discussed.