Two-gap superconductivity and topological surface states in TaOsSi

作者：Chunqiang Xu, Bin Li, Jiaqi Feng, Wen‐He Jiao, Yu-Xuan Li, S. W. Liu, Yuxing Zhou, Raman Sankar, N. D. Zhigadlo, H. B. Wang, Zhida Han, Bin Qian, W. Ye, Wei Zhou, T. Shiroka, Pabitra Kumar Biswas⃰, Xiaofeng Xu, Zhixiang Shi · 发表于：Physical review. B./Physical review. B · 年份：2019 · DOI：10.1103/physrevb.100.134503 · 被引用次数：28 · 研究领域：Topological Materials and Phenomena、Graphene research and applications、Advanced Condensed Matter Physics

The occurrence of superconductivity in topological materials is considered as a promising route for realizing topological superconductors, a platform able to host the long-sought Majorana fermions in condensed matter. In this work, by using electrical transport and heat-capacity measurements, as well as first-principles band-structure calculations, we investigate the physical properties of TaOsSi, a superconductor with ${T}_{c}\ensuremath{\approx}5.8$ K. The behavior of both its upper critical field and low-temperature heat-capacity suggest the existence of two superconducting gaps. More strikingly, first-principles calculations reveal gapless topological surface states in the present material. The evolution of the electrical resistivity with pressure (up to 50 GPa) was also investigated, and a ``V-shaped'' diagram of ${T}_{c}$ vs $P$ was found. Overall, our data suggest that TaOsSi is a new system where multiband superconductivity and topological surface states coexist and, hence, it may serve as a possible candidate in the search for topological superconductivity.