Fe(Se,Te) films of different thicknesses were deposited on metal tapes by pulsed laser deposition at different substrate temperatures. It is found that the substrate temperature dependence of superconductivity changes with the Fe(Se,Te) film thickness. When fabricating thin Fe(Se,Te) films with a thickness of about 150 nm, moderate substrate temperatures are conducive to balancing the influence of texture and stoichiometry on superconductivity, contributing to the obtainment of good superconductivity. When the Fe(Se,Te) films’ thickness is about 300 nm, the optimal substrate temperatures are lowered due to the determination of film superconductivity by the inhomogeneity of longitudinal chalcogen distribution via the cooperation of Te loss in the long-term-ablated target and the attraction of metal ions in the buffer layer. In addition, with a further increase in thickness from 300 to 600 nm, the self-field critical current of thick Fe(Se,Te) films continuously increases, but the critical current density increases first and then decreases, which is thought to be a result of the misoriented grains or non-superconducting phase due to the large deviation between the actual deposition temperature and the set substrate temperature, and the Se excess in the film. In addition, the 450-nm-thick Fe(Se,Te) film exhibits excellent self-field and in-field performances at 4.2 K: 1.308 MA/cm2 at self-field and over 0.5 MA/cm2 at 9 T. Point pinning, which is the local lattice disturbance randomly distributed in the film observed by transmission electron microscopy, dominates over the entire temperature range.

Previous research results have demonstrated that Fe(Se,Te) films with high critical current density Jc can be realized on flexible metal substrates and are promising for high field applications at 4.2 K. For practical applications, the length of the coated conductor is a key factor. Regarding the fabrication of long Fe(Se,Te)‐coated conductor tapes, the biggest difficulty is how to achieve a breakthrough from static coating to continuous dynamic coating process. Herein, it is demonstrated that Fe(Se,Te)‐coated conductor with high superconducting performance can be continuously fabricated. 1 m‐long Fe(Se,Te)‐coated conductors have been successfully fabricated by multiturn pulsed laser deposition on CeO2‐buffered ion beam‐assisted deposition MgO tape. The Fe(Se,Te)‐coated conductors have high critical temperature of 17.5 K and Jc over 2 MA cm−2 at 4.2 K and self‐field. The end‐to‐end critical current of 1 m‐long Fe(Se,Te)‐coated conductor is as high as 108 A cm−1‐width at 4.2 K and self‐field, and the corresponding Jc is 1.54 MA cm−2, which is above the threshold for industrial applications. The upper critical field at 0 K is deduced to be about 53 T. To the best of knowledge, this is the first demonstration of continuous fabrication of long Fe(Se,Te)‐coated conductors with high performance.

Iron chalcogenide Fe(Se,Te) films with thicknesses of 150 nm were deposited on CeO2-buffered metal tapes via pulsed laser deposition using various laser fluences. The film crystallinity and stoichiometry improved upon increasing the laser fluence. This was explained by the ablation threshold that the superconducting performance was better at higher laser fluences and was attributed to the joint contribution of higher Te contents, better texture, and strengthened in-plane strain. In addition, the pinning mechanism was studied by analyzing the in-field performance characteristics of the Fe(Se,Te) films. The dominant pinning center remained point pinning and was independent of the magnetic field direction and temperature. A collective pinning theory-based analysis showed that the vortex pinning behavior in the Fe(Se,Te) film varied from δ l pinning to δ Tc pinning as the temperature approached the critical temperature. This was related to film superconductivity inhomogeneity, which was driven by unreacted Se and Te atoms.

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