Figure 4. Predicted J_c across the YBCO phase diagram.

Map of J_c(sf) across the phase diagram for Y_0.8Ca_0.2Ba₂Cu₃O_y calculated from the superfluid density23,24 using equation (4). A sharp peak is centred on the critical doping where the pseudogap T* line falls to zero (solid white curve). The triangles show the low-T data points for T* reported from field-dependent resistivity29. A second smaller peak is predicted just below P≈0.12 where charge ordering has been reported33. The circles are T_c data points.