Dual topological superconducting states in the layered titanium-based oxypnictide superconductor BaTi$_2$Sb$_2$O

作者：Zhe Huang, Wenyan Liu, H. Y. Wang, Ying Su, Z. T. Liu, Xiaoyan Shi, Shang Gao, Zhicheng Jiang, Zuhui Liu, J. S. Liu, Xiancong Lu, Yi-feng Yang, J. X. Zhang, Shuchun Huan, Xia, W., Jia-Heng Wang, Yi-Dong Wu, X. Wang, Na Yu, Y. B. Huang, Shuang Qiao, Jun Li, Weiwei Zhao, Y. F. Guo, Guichuan Li, Dawei Shen · 发表于：arXiv (Cornell University) · 年份：2020 · DOI：10.48550/arxiv.2009.06805 · 研究领域：Topological Materials and Phenomena、Diamond and Carbon-based Materials Research、Advanced Materials Characterization Techniques

Topological superconductors have long been predicted to host Majorana zero modes which obey non-Abelian statistics and have potential for realizing non-decoherence topological quantum computation. However, material realization of topological superconductors is still a challenge in condensed matter physics. Utilizing high-resolution angle-resolved photoemission spectroscopy and first-principles calculations, we predict and then unveil the coexistence of topological Dirac semimetal and topological insulator states in the vicinity of Fermi energy ($E_F$) in the titanium-based oxypnictide superconductor BaTi$_2$Sb$_2$O. Further spin-resolved measurements confirm its spin-helical surface states around $E_F$, which are topologically protected and give an opportunity for realization of Majorana zero modes and Majorana flat bands in one material. Hosting dual topological superconducting states, the intrinsic superconductor BaTi$_2$Sb$_2$O is expected to be a promising platform for further investigation of topological superconductivity.