Two superconducting phases induced at point contacts on the Weyl semimetal TaAs

作者：Xingyuan Hou, Yadong Gu, Shujing Li, Lingxiao Zhao, Wenliang Zhu, Zong Wang, Mengdi Zhang, Fan Zhang, Lu Zhang, Hai Zi, Yanwei Wu, Huai-Xin Yang, Zhi-An Ren, Ping Zhang, Genfu Chen, Ning Hao, Lei Shan · 发表于：Physical review. B./Physical review. B · 年份：2020 · DOI：10.1103/physrevb.101.134503 · 被引用次数：16 · 研究领域：Topological Materials and Phenomena、Graphene research and applications、Advanced Condensed Matter Physics

Tip-induced superconductivity at point contacts on the nonsuperconducting Weyl semimetal TaAs has been reported recently. Meanwhile, both the main tetragonal phase and the intergrown hexagonal phase of TaAs were identified to be topologically nontrivial according to theoretical calculations. Here, we report the observation of two independent local superconducting states induced at the point contacts formed on TaAs, which exhibit distinct temperature dependencies of the critical magnetic field ${H}_{c2}(T)$. A universal relationship between ${H}_{c2}(0)$, ${T}_{c}$, and the Fermi velocities of bulk bands near Weyl points of the two TaAs phases was uncovered, demonstrating the dominant role of the bulk bands in the emergence of superconductivity, rather than the surface states. These results provide a direction to study the mechanism of the tip-induced superconductivity in topological semimetals.