准二维拓扑非平凡YbBi$_2$中的I型超导电性
Type-I superconductivity in a quasi-2D topologically nontrivial YbBi$_2$
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中文总结 AI 辅助
本研究报道YbBi$_2$中低于0.9 K的体I型超导电性，结合轻载流子与非零贝里相位，为拓扑非平凡环境中的超导研究提供独特平台。
中文摘要 AI 辅助
在具有非平凡电子拓扑的化学计量材料中，本征超导电性仍然罕见，这限制了研究这两种现象如何在单一电子系统中共存的机会。在此，我们报道了YbBi$_2$中低于$T_c$ $\sim$ 0.9 K的体I型超导电性，YbBi$_2$是一种具有非对称晶体结构和准二维费米面的层状稀土化合物。热力学和输运测量确定了超导基态，而量子振荡揭示了异常轻的载流子，其回旋质量低至0.07 $m_e$，以及约0.82 $\pi$的非零贝里相位。后者与对称性保护的能带简并附近相应轨道的威尔逊相位计算值0.99 $\pi$密切匹配。ARPES测量显示与计算电子结构的关键特征良好一致，为正常态能带结构提供了补充的实验约束。本征I型超导电性、轻准二维载流子以及非平凡电子拓扑迹象的结合，将YbBi$_2$确定为研究拓扑非平凡电子环境中超导电性的独特化学计量平台。
英文摘要
Intrinsic superconductivity in stoichiometric materials with nontrivial electronic topology remains uncommon, limiting opportunities to investigate how these two phenomena coexist within a single electronic system. Here, we report bulk type-I superconductivity below $T_c$ $\sim$ 0.9~K in YbBi$_2$, a layered rare-earth compound with a nonsymmorphic crystal structure and a quasi-two-dimensional Fermi surface. Thermodynamic and transport measurements establish the superconducting ground state, while quantum oscillations reveal exceptionally light carriers, with a cyclotron mass as low as 0.07 $m_e$, and a nonzero Berry phase of approximately 0.82 $π$. The latter closely matches the calculated value of the corresponding Wilson phase 0.99 $π$ for the corresponding orbit near a symmetry-protected band degeneracy. ARPES measurements show good agreement with key features of the calculated electronic structure, providing complementary experimental constraints on the normal-state band structure. The combination of intrinsic type-I superconductivity, light quasi-two-dimensional carriers, and signatures of nontrivial electronic topology identifies YbBi$_2$ as a distinct stoichiometric platform for investigating superconductivity in a topologically nontrivial electronic environment.
发表机构
- Oak Ridge National Laboratory（橡树岭国家实验室）
- Gdansk University of Technology（格但斯克理工大学）
- National High Magnetic Field Laboratory, Los Alamos National Laboratory（洛斯阿拉莫斯国家实验室国家高磁场实验室）
- AGH University of Krakow（克拉科夫AGH科技大学）
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