Particle-hole mixed Bogoliubov quasiparticles and Cooper instability in single-unit-cell FeSe/SrTiO3 films

IF 7.5 Q1 MATERIALS SCIENCE, MULTIDISCIPLINARY

Communications Materials Pub Date : 2024-07-06 DOI:10.1038/s43246-024-00554-9

Zhiyuan Wei, Shaozhi Li, Bo Liu, Xiupeng Sun, Yinqi Hu, Shuai Sun, Shuting Peng, Yang Luo, Linwei Huai, Jianchang Shen, Bingqian Wang, Yu Miao, Zhipeng Ou, Yao Wang, Kun Jiang, Junfeng He

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Abstract

In conventional superconductors, Bogoliubov quasiparticles and Cooper instability provide a paradigm to describe the superconducting state and the superconducting transition, respectively. However, whether these concepts can be adapted to describe Fe-based superconductors requires rigorous examinations from experiments. Here, we report angle-resolved photoemission studies on single-layer FeSe films grown on SrTiO3 substrate. Due to the improved clarity, our results reveal both particle and hole branches of the energy band with clear quasiparticles. The dispersion and coherence factors are extracted, which unveil the particle-hole mixed Bogoliubov quasiparticles in the superconducting state of the FeSe/STO films. Effective pairing susceptibility is also deduced as a function of temperature, which indicates the persistence of Cooper instability in Fe-based superconductors. It is still under debate whether unconventional superconductors can still be described in terms of Bogoliubov quasiparticles in the superconducting state. Here, angle-resolved photoemission spectroscopy measurements on FeSe/SrTiO3 films reveal particle-hole mixed Bogoliubov quasiparticles, despite the likely unconventional pairing mechanism.

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单单元电池 FeSe/SrTiO3 薄膜中的粒子-空穴混合波哥留布夫准粒子和库珀不稳定性

在传统超导体中，Bogoliubov 准粒子和库珀不稳定性分别为描述超导状态和超导转变提供了范例。然而，这些概念能否适用于描述铁基超导体，还需要实验的严格检验。在此，我们报告了在 SrTiO3 衬底上生长的单层 FeSe 薄膜的角度分辨光发射研究。由于清晰度的提高，我们的结果揭示了能带的粒子和空穴分支，并具有清晰的准粒子。通过提取弥散因子和相干因子，我们揭示了 FeSe/STO 薄膜超导态中的粒子-空穴混合 Bogoliubov 准粒子。此外，还推导出了有效配对感度与温度的函数关系，这表明在铁基超导体中存在库珀不稳定性。非常规超导体是否仍能用超导状态下的波哥留布夫准粒子来描述，目前仍存在争议。在这里，对 FeSe/SrTiO3 薄膜进行的角度分辨光发射光谱测量揭示了粒子-空穴混合的 Bogoliubov 准粒子，尽管其配对机制可能是非常规的。

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来源期刊

Communications Materials MATERIALS SCIENCE, MULTIDISCIPLINARY-

CiteScore

12.10

自引率

1.30%

发文量

审稿时长

17 weeks

期刊介绍： Communications Materials, a selective open access journal within Nature Portfolio, is dedicated to publishing top-tier research, reviews, and commentary across all facets of materials science. The journal showcases significant advancements in specialized research areas, encompassing both fundamental and applied studies. Serving as an open access option for materials sciences, Communications Materials applies less stringent criteria for impact and significance compared to Nature-branded journals, including Nature Communications.