Superconductivity and hole doping in Pr0.5Ca0.5Ba2Cu3O7−δ thin films

Abstract

We have grown superconducting ${\mathrm{Pr}}_{0.5}$ ${\mathrm{Ca}}_{0.5}$ ${\mathrm{Ba}}_2$ ${\mathrm{Cu}}_3$ ${\mathrm{O}}_{7\mathrm{-}\mathrm{\delta }}$ epitaxial thin films that exhibit a superconducting onset temperature of 43 K with ${\mathit{T}}_{\mathit{c}}$(R=0)=34.9 K. This is the first time, to our knowledge, that 1:2:3-phase superconductivity has been achieved by substituting Ca for Pr, without the presence in the alloy of Υ or any other rare-earth element R for which R${\mathrm{Ba}}_2$ ${\mathrm{Cu}}_3$ ${\mathrm{O}}_{7\mathrm{-}\mathrm{\delta }}$ is superconducting. This result supports the view that hole localization/filling contributes substantially to the suppression of superconductivity by Pr in ${\mathrm{PrBa}}_2$ ${\mathrm{Cu}}_3$ ${\mathrm{O}}_{7\mathrm{-}\mathrm{\delta }}$, and clearly demonstrates that this suppression can be compensated by appropriate hole doping with Ca.