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arXiv · 2311.07943

Superconductivity above 30 K due to the introduction of oxygen in CaFeAsF

Yixin Liu·Teng Wang·Zulei Xu·Da Jiang·Yi Zhao·Yanpeng Qi·Xiaoni Wang·Ming Yang·Mao Ye·Wei Peng·Gang Mu
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Abstract

Exploring new unconventional superconductors is of great value for both fundamental research and practical applications. It is a long-term challenge to develop and study more hole-doped superconductors in 1111 system of iron-based superconductors. Here we report the discovery of superconductivity with a critical transition temperature up to 30.7 K in the compound CaFeAsF by a post-annealing treatment in air atmosphere. The superconducting behaviors are verified in both the single-crystalline and polycrystalline samples by the resistance and magnetization measurements. The analysis by combining the depth-resolved time-of-flight secondary ion mass spectrometry (TOF-SIMS) and X-ray photoelectron spectroscopy (XPS) measurements shows that the introduction of oxygen elements and the consequent changing in Fe valence by the annealing treatment may lead to the hole-type doping, which is the origin for the occurrence of superconductivity. Our results pave the way for further in-depth investigations on the hole-doped 1111 system in iron-based superconductors.

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Yixin Liu, Teng Wang, Zulei Xu, Da Jiang, Yi Zhao, Yanpeng Qi, Xiaoni Wang, Ming Yang, Mao Ye, Wei Peng, Gang Mu. 2023-11-14. Superconductivity above 30 K due to the introduction of oxygen in CaFeAsF. https://doi.org/10.1039/d4tc03994g

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