Pressure-induced superconductivity in Bi-doped BaFe₂(As_1–xBi_x)₂ single crystals

This study systematically investigates the transport and point-contact Andreev reflection spectroscopy (PCARS) properties of Bi-doped BaFe₂ (As_1−xBi_x)₂ crystals under high pressures up to 8.7 GPa. The superconducting critical temperature (T_c) and upper critical field (H_c2) initially decrease with pressure but exhibit a local maximum around 2.9 GPa before further suppression, which can be related to the superconducting transition in the parent compound. The conductance spectrum is consistent with a two-band s-wave model, confirming multi-band superconductivity. The superconducting energy gaps and coupling strengths decrease monotonically with pressure, with the larger gap transitioning from strong to weak coupling. These results provide insight into the interplay between structural, electronic, and superconducting properties in isovalent-doped 122 Fe-based superconductors.