Complete electronic phase diagram and enhanced superconductivity in fluorine-doped PrFeAsO1-xFx

Abstract

Establishing a complete electronic phase diagram for REFeAsO (RE = rare earth, RE1111) ironbased superconductors has remained experimentally challenging. Here, we report a systematic investigation of PrFeAsO1-xFx over the full nominal fluorine-doping range 0 to 1 and construct the first comprehensive electronic phase diagram for this system. The evolution from the nonsuperconducting parent compound to the fluorine-rich limit reveals a broad dome shaped superconducting region. Structural refinement demonstrates a systematic lattice contraction with increasing fluorine content (x), corroborated by Raman spectroscopy through softening of the Pr(A1g) phonon mode and hardening of the Fe(B1g) mode, confirming effective fluorine incorporation at the oxygen sites. The maximum superconducting transition temperature (Tc) reaches up to 52.3 K, approximately 5 K higher than previous reports for Pr1111. Magnetotransport measurements yield large upper critical fields Hc2(0) exceeding 100 T, while analysis of resistive transition broadening reveals thermally activated flux flow with a crossover from single-vortex to collective pinning regimes. Specific-heat measurements exhibit a reduced jump deltaC/{\gamma}Tc < 1.43, reflecting strong superconducting fluctuations and multiband pairing. These results establish clear structure property correlations and provide a unified description of superconductivity across the entire doping range of the Pr1111 system.