Extremely strong coupling s-wave superconductivity in the medium-entropy alloy TiHfNbTa

Lingyong Zeng; Xunwu Hu; Mebrouka Boubeche; Kuan Li; Longfu Li; Peifei Yu; Kangwang Wang; Chao Zhang; Kui Jin; DaoXin Yao; Huixia Luo

arXiv · 2308.14612

Extremely strong coupling s-wave superconductivity in the medium-entropy alloy TiHfNbTa

Lingyong Zeng·Xunwu Hu·Mebrouka Boubeche·Kuan Li·Longfu Li·Peifei Yu·Kangwang Wang·Chao Zhang·Kui Jin·DaoXin Yao·Huixia Luo

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Abstract

Here we report a TiHfNbTa bulk medium-entropy alloy (MEA) superconductor crystallized in the body-centered cubic structure, which is synthesized by an arc melting method. Superconducting properties of the TiHfNbTa are studied by employing magnetic susceptibility, resistivity, and specific heat measurements. Experimental results show a bulk superconducting transition temperature (Tc) of around 6.75 K. The lower and upper crit-ical fields for TiHfNbTa are 45.8 mT and 10.46 T, respectively. First-principles calculations show that the d electron of Ti, Hf, Nb, and Ta is the main contribution near the Fermi level. Our results indicate that the superconductivity is a conven-tional s-wave type with extremely strong coupling. The extremely strong coupling behavior in the s-wave type TiHfNbTa MEA superconductor is unusual because it generally happens in cuprates, pnictides, and other unconventional superconductors.

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Lingyong Zeng, Xunwu Hu, Mebrouka Boubeche, Kuan Li, Longfu Li, Peifei Yu, Kangwang Wang, Chao Zhang, Kui Jin, DaoXin Yao, Huixia Luo. 2023-08-28. Extremely strong coupling s-wave superconductivity in the medium-entropy alloy TiHfNbTa. https://arxiv.org/abs/2308.14612

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