Heat capacity jump at Tc and pressure derivatives of superconducting transition temperature in the Ba1-xKxFe2As2 (0.2 ≤ x ≤ 1.0) series

We present the evolution of the initial (up to similar to 10 kbar) hydrostatic pressure dependencies of T-c and of the ambient pressure jump in the heat capacity associated with the superconducting transition as a function of K doping in the Ba1-xKxFe2As2 family of iron-based superconductors. The pressure derivatives show a weak but distinct anomaly near x similar to 0.7. In the same concentration region, Delta C-p vertical bar(Tc) deviates from the Delta C-p proportional to T-3 scaling found for most BaFe2As2-based superconductors. These results are consistent with a possible significant modification of the superconducting state, occurring near x similar to 0.7. DOI: 10.1103/PhysRevB.87.100509