Figure 1

(Color online) The temperature dependences of the magnetic susceptibility normalized to that for an ideal superconduc-tor of spherical shape $\chi \left(T\right)∕{\chi }_{\mathit{id}}$ for ${}^{16}\mathrm{O}∕{}^{18}\mathrm{O}$ substituted ${\mathrm{Y}}_{0.8}{\mathrm{Pr}}_{0.2}{\mathrm{Ba}}_2{\mathrm{Cu}}_3{\mathrm{O}}_{7-\delta }$.Reuse & Permissions

Figure 2

(Color online) (a) Temperature dependences of the inverse-squared in-plane magnetic field penetration depth ${\lambda }_{ab}^{-2}$ for ${}^{16}\mathrm{O}∕{}^{18}\mathrm{O}$ substituted ${\mathrm{Y}}_{1-x}{\mathrm{Pr}}_x{\mathrm{Ba}}_2{\mathrm{Cu}}_3{\mathrm{O}}_{7-\delta }$ $(x=0.0,0.2,0.3,0.45)$ samples. The solid lines are results from a numerical analysis as described in the text. (b) ${\lambda }_{ab}^{-2}\left(T\right)$ for back-exchanged (${}^{16}\mathrm{O}\to {}^{18}\mathrm{O}$, ${}^{18}\mathrm{O}\to {}^{16}\mathrm{O}$) ${\mathrm{Y}}_{1-x}{\mathrm{Pr}}_x{\mathrm{Ba}}_2{\mathrm{Cu}}_3{\mathrm{O}}_{7-\delta }$ $(x=0.2,0.3)$, showing that the doping level for the ${}^{16}\mathrm{O}∕{}^{18}\mathrm{O}$ samples is unchanged.Reuse & Permissions

Figure 3

(Color online) The zero-temperature superconducting gap ${\Delta }_0$ vs the superconducting transition temperature $T_c$ for ${}^{16}\mathrm{O}∕{}^{18}\mathrm{O}$ substituted ${\mathrm{Y}}_{1-x}{\mathrm{Pr}}_x{\mathrm{Ba}}_2{\mathrm{Cu}}_3{\mathrm{O}}_{7-\delta }$ samples studied in the present work and various hole-doped HTSs studied by means of Andreev reflection (AR) (Ref. 25) muon-spin rotation $\left(\mu \mathrm{SR}\right)$ (Refs. 26, 27, 28), tunneling (Refs. 29, 30, 31), Raman scattering (RS) (Ref. 32) and angle-resolved photoemission spectroscopy (ARPES) (Ref. 33) techniques. Solid red and blue circles are the ${\mathrm{Y}}_{1-x}{\mathrm{Pr}}_x{\mathrm{Ba}}_2{\mathrm{Cu}}_3{\mathrm{O}}_{7-\delta }$ data obtained in the present study (see Table ). Open circles, square, and up and down triangles are the data for $\mathrm{Y}{\mathrm{Ba}}_2{\mathrm{Cu}}_3{\mathrm{O}}_{7-\delta }$ (Refs. 25, 28) and ${\mathrm{Y}}_{1-y}{\mathrm{Ca}}_y{\mathrm{Ba}}_2{\mathrm{Cu}}_3{\mathrm{O}}_{7-\delta }$ (Ref. 29) (Y123). The crossed circle is the data point for $\mathrm{Y}{\mathrm{Ba}}_2{\mathrm{Cu}}_4{\mathrm{O}}_8$ (Y124) from Ref. 27. Open diamonds and the crossed square are the data for ${\mathrm{La}}_{2-x}{\mathrm{Sr}}_x\mathrm{Cu}{\mathrm{O}}_4$ (La214) from Refs. 26, 32. The open hexagon corresponds to Pb doped ${\mathrm{Bi}}_2{\mathrm{Sr}}_2\mathrm{Cu}{\mathrm{O}}_{6+x}$ (Bi2201) (Ref. 30) and the stars represent the data for ${\mathrm{Bi}}_2{\mathrm{Sr}}_2{\mathrm{Ca}}_{(1-x)}{\mathrm{Y}}_x{\mathrm{Cu}}_2{\mathrm{O}}_8$ (Bi2212) (Ref. 33). The shaded gray area has been extracted from Ref. 31 where $2{\Delta }_0∕k_B{T}_c=7.9\left(5\right)$ was observed for Bi2212. The solid line corresponding to $2{\Delta }_0∕k_B{T}_c=5.34$ has been predicted theoretically by using a two-component model with polaronic coupling (Ref. 34). The dashed line corresponds to the BCS value $2{\Delta }_0∕k_B{T}_c=3.52$.Reuse & Permissions

Figure 4

(Color online) Comparison of the oxygen-isotope shift on the superconducting gap ${\Delta }_0$ with the one on the transition temperature $T_c$ for ${\mathrm{Y}}_{1-x}{\mathrm{Pr}}_x{\mathrm{Ba}}_2{\mathrm{Cu}}_3{\mathrm{O}}_{7-\delta }$ $(x=0.0,0.2,0.3,0.45)$. The circles refer to the present experiments, and the solid line was obtained from model calculations as described in Refs. 34, 35, 36. The stars refer to the back-exchange data.Reuse & Permissions