Effects of Te- and Fe-doping on the superconducting properties in FeySe1-xTex thin films

doi:10.21203/rs.3.rs-847481/v1

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Research Article

Effects of Te- and Fe-doping on the superconducting properties in Fe_ySe_1-xTe_x thin films

https://doi.org/10.21203/rs.3.rs-847481/v1

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High quality Fe_ySe_1−xTe_x epitaxial thin films have been fabricated on TiO₂-buffered SrTiO₃ substrates by pulsed laser deposition technology. There is a significant composition deviation between the nominal target and the thin film. Te doping can affect the Se/Te ratio and Fe content in chemical composition. The superconducting transition temperature T_c is closely related to the chemical composition. Fe vacancies are beneficial for the Fe_ySe_1−xTe_x films to exhibit the higher T_c. A 3D phase diagram is given that the optimize range is x = 0.13 − 0.15 and y = 0.73 − 0.78 for Fe_ySe_1−xTe_x films. The anisotropic, effective pining energy and critical current density for the Fe_0.72Se_0.94Te_0.06, Fe_0.76Se_0.87Te_0.13 and Fe_0.91Se_0.77Te_0.23 samples were studied in detail. The scanning transmission electron microscopy images display a regular pattern without obviously scale defects at the interfacial structure.