Yang Hao, Li Yao-Yi, Liu Teng-Teng, Guan Dan-Dan, Wang Shi-Yong, Zheng Hao, Liu Canhua, Fu Liang, Jia Jin-Feng
Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Shenyang National Laboratory for Materials Science, School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China.
CAS Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijing 100190, China.
Phys Rev Lett. 2020 Sep 25;125(13):136802. doi: 10.1103/PhysRevLett.125.136802.
Superconducting topological crystalline insulators (TCIs) have been proposed to be a new type of topological superconductor where multiple Majorana zero modes may coexist under the protection of lattice symmetries. The bulk superconductivity of TCIs has been realized, but it is quite challenging to detect the superconductivity of topological surface states inside their bulk superconducting gaps. Here, we report high-resolution scanning tunneling spectroscopy measurements on lateral Sn_{1-x}Pb_{x}Te-Pb heterostructures using superconducting tips. Both the bulk superconducting gap and the multiple in-gap states with energy differences of ∼0.3 meV can be clearly resolved on TCI Sn_{1-x}Pb_{x}Te at 0.38 K. Quasiparticle interference measurements further confirm the in-gap states are gapless. Our work demonstrates that the unique topological superconductivity of a TCI can be directly distinguished in the density of states, which helps to further investigate the multiple Dirac and Majorana fermions inside the superconducting gap.
超导拓扑晶体绝缘体（TCIs）被认为是一种新型拓扑超导体，在晶格对称性的保护下，多个马约拉纳零模可能共存。TCIs的体超导性已经实现，但在其体超导能隙内检测拓扑表面态的超导性颇具挑战。在此，我们报告了使用超导针尖对横向Sn_{1-x}Pb_{x}Te-Pb异质结构进行的高分辨率扫描隧道谱测量。在0.38 K温度下，在TCI Sn_{1-x}Pb_{x}Te上可以清晰分辨出体超导能隙以及能量差约为0.3 meV的多个能隙内态。准粒子干涉测量进一步证实能隙内态是无隙的。我们的工作表明，TCI独特的拓扑超导性可以在态密度中直接区分出来，这有助于进一步研究超导能隙内的多个狄拉克费米子和马约拉纳费米子。
