Evidence of topological edge states in a superconducting nonsymmorphic nodal-line semimetal

Abstract

Topological materials host fascinating low dimensional gapless states at the boundary. As a prominent example, helical topological edge states (TESs) of two-dimensional topological insulators (2DTIs) and their stacked three-dimensional (3D) equivalent, weak topological insulators (WTIs), have sparked research enthusiasm due to their potential application in the next generation of electronics/spintronics with low dissipation. Here, we propose layered superconducting material CaSn as a WTI with nontrivial Z2 as well as nodal line semimetal protected by crystalline non-symmorphic symmetry. Our systematic angle-resolved photoemission spectroscopy (ARPES) investigation on the electronic structure exhibits excellent agreement with the calculation. Furthermore, scanning tunnelling microscopy/spectroscopy (STM/STS) at the surface step edge shows signatures of the expected TES. These integrated evidences from ARPES, STM/STS measurement and corresponding ab initio calculation strongly support the existence of TES in the non-symmorphic nodal line semimetal CaSn, which may become a versatile material platform to realize multiple exotic electronic states as well as topological superconductivity.

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Cited by in corpus (4)

• Higher-order topological superconductors based on weak topological insulators
• Topology hierarchy of transition metal dichalcogenides built from quantum spin Hall layers
• Machine learning search for stable binary Sn alloys with Na, Ca, Cu, Pd, and Ag
• Nontrivial topological states in BaSn5 superconductor probed by de Haas-van Alphen quantum oscillations