1. The origin of the large T c $T_{\mathrm{c}}$ variation in FeSe thin films probed by dual-beam pulsed laser deposition
- Author
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Zhongpei Feng, Hua Zhang, Jie Yuan, Xingyu Jiang, Xianxin Wu, Zhanyi Zhao, Qiuhao Xu, Valentin Stanev, Qinghua Zhang, Huaixin Yang, Lin Gu, Sheng Meng, Suming Weng, Qihong Chen, Ichiro Takeuchi, Kui Jin, and Zhongxian Zhao
- Subjects
High-temperature superconductivity ,Iron chalcogenide superconductors ,Pulsed laser deposition ,High-throughput technique ,Atomic physics. Constitution and properties of matter ,QC170-197 - Abstract
Abstract FeSe is one of the most enigmatic superconductors. Among the family of iron-based compounds, it has the simplest chemical makeup and structure, and yet it displays superconducting transition temperature ( T c $T_{\text{c}}$ ) spanning 0 to 15 K for thin films, while it is typically 8 K for single crystals. This large variation of T c $T_{\text{c}}$ within one family underscores a key challenge associated with understanding superconductivity in iron chalcogenides. Here, using a dual-beam pulsed laser deposition (PLD) approach, we have fabricated a unique lattice-constant gradient thin film of FeSe which has revealed a clear relationship between the atomic structure and the superconducting transition temperature for the first time. The dual-beam PLD that generates laser fluence gradient inside the plasma plume has resulted in a continuous variation in distribution of edge dislocations within a single film, and a precise correlation between the lattice constant and T c $T_{\text{c}}$ has been observed here, namely, T c ∝ c − c 0 $T_{\text{c}} \propto \sqrt{c- c_{0}}$ , where c is the c-axis lattice constant (and c 0 $c_{0}$ is a constant). This explicit relation in conjunction with a theoretical investigation indicates that it is the shifting of the d xy $d_{\text{xy}}$ orbital of Fe which plays a governing role in the interplay between nematicity and superconductivity in FeSe.
- Published
- 2024
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