One-unit-cell FeSe films on SrTiO₃ substrates are of great interest owing to significantly enlarged pairing gaps characterized by two coherence peaks at ±10 meV and ±20 meV. In-situ transport measurement is desired to reveal novel properties. Here, we performed in-situ microscale electrical transport and combined scanning tunneling microscopy measurements on continuous one-unit-cell FeSe films with twin boundaries. We observed two spatially coexisting superconducting phases in domains and on boundaries, characterized by distinct superconducting gaps (\({\Delta }_{1}\)~15 meV vs. \({\Delta }_{2}\)~10 meV) and pairing temperatures (T_p1~52.0 K vs. T_p2~37.3 K), and correspondingly two-step nonlinear \(V \sim {I}^{\alpha }\) behavior but a concurrent Berezinskii–Kosterlitz–Thouless (BKT)-like transition occurring at \({T}_{{{{{{\rm{BKT}}}}}}}\)~28.7 K. Moreover, the onset transition temperature \({T}_{{{{{{\rm{c}}}}}}}^{{{{{{\rm{onset}}}}}}}\)~54 K and zero-resistivity temperature \({T}_{{{{{{\rm{c}}}}}}}^{{{{{{\rm{zero}}}}}}}\)~31 K are consistent with T_p1 and \({T}_{{{{{{\rm{BKT}}}}}}}\), respectively. Our results indicate the broadened superconducting transition in FeSe/SrTiO₃ is related to intrinsic electronic inhomogeneity due to distinct two-gap features and phase fluctuations of two-dimensional superconductivity.

_{SrTiO 3}基底上的单胞 FeSe 薄膜引起了人们的极大兴趣，因为其配对间隙显着增大，其特征在于 ±10 meV 和 ±20 meV 处有两个相干峰。需要进行原位传输测量来揭示新颖的特性。在这里，我们对具有孪晶边界的连续单胞 FeSe 薄膜进行了原位微尺度电传输和组合扫描隧道显微镜测量。我们在域和边界上观察到两个空间共存的超导相，其特征是不同的超导间隙 ( \({\Delta }_{1}\) ~15 meV vs. \({\Delta }_{2}\) ~10 meV) 和配对温度 ( T _p1 ~52.0 K vs. T _p2 ~37.3 K)，以及相应的两步非线性\(V \sim {I}^{\alpha }\)行为，但同时存在 Berezinskii–Kosterlitz–Thouless类 (BKT) 转变发生在\({T}_{{{{{{\rm{BKT}}}}}}}\) ~28.7 K。此外，起始转变温度\({T}_{ {{{{{\rm{c}}}}}}}^{{{{{{\rm{开始}}}}}}}\) ~54 K 和零电阻率温度\({T}_ {{{{{{\rm{c}}}}}}}^{{{{{{\rm{zero}}}}}}}\) ~31 K 与T _p1和\({T }_{{{{{{\rm{BKT}}}}}}}\)分别。我们的结果表明，FeSe/SrTiO ₃中展宽的超导转变与二维超导性的独特的两能隙特征和相位波动导致的固有电子不均匀性有关。