Spatial inhomogeneity of superconducting gap in epitaxial monolayer FeTe1−xSex films

Yaowu Liu; Luxin Li; Zheng Xie; Zichun Zhang; Sidan Chen; Lichen Ji; Wei Chen; Xinyu Zhou; Xiaopeng Hu; Xi Chen; Qi-Kun Xue; Shuai-Hua Ji

doi:10.1103/PhysRevB.108.214514

Spatial inhomogeneity of superconducting gap in epitaxial monolayer FeTe1−xSex films

Yaowu Liu, Luxin Li, Zheng Xie, Zichun Zhang, Sidan Chen, Lichen Ji, Wei Chen, Xinyu Zhou, Xiaopeng Hu, Xi Chen, Qi-Kun Xue, Shuai-Hua Ji

DOI 10.1103/PhysRevB.108.214514 · Physical Review B

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Abstract

Monolayer FeTe1−xSex films grown on a SrTiO3(001) substrate is a promising platform to explore both high-temperature and topological superconductivity. Using molecular beam epitaxy, we successfully synthesized monolayer FeTe1−xSex films (0≤x≤1) on a Nb-doped SrTiO3(001) substrate. The as-grown films with 0.30≤x≤1 show superconductivity. By spatially mapping the superconducting gap distribution, we found a large gap variation of ∼3–7meV. Our analysis shows that impurities/defects and local chemical composition variation play a minor role in the superconducting gap inhomogeneity. The large gap variation is possibly attributed to the joint effects of the interface inhomogeneity and inhomogeneous superfluid. Our study sheds light on the fundamental properties of two-dimensional iron-based superconductors.

Source-reported materials — not catalogue approval

Formula	Reported Tc (K)	Pressure (GPa)	Type
FeTe1-xSex Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	—	Pressure not reported	unknown
FeSe Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	90	Pressure not reported	onset