De Haas-van Alphen Quantum Oscillations in BaSn3 Superconductor with Multiple Dirac Fermions**Supported by the National Natural Science Foundation of China (Grant No. 11874264), the Strategic Priority Research Program of Chinese Academy of Sciences (Grant No. XDA18000000), the Starting Grant of ShanghaiTech University, the Shenzhen Peacock Team Plan (Grant No. KQTD20170809110344233), the Bureau of Industry and Information Technology of Shenzhen through

Abstract

Characterization of Fermi surface of the BaSn3 superconductor (Tc ∼ 4.4 K) by de Haas–van Alphen (dHvA) effect measurement reveals its non-trivial topological properties. Analysis of non-zero Berry phase is supported by the ab initio calculations, which reveals a type-II Dirac point setting and tilting along the high symmetric K–H line of the Brillouin zone, about 0.13 eV above the Fermi level, and other two type-I Dirac points on the high symmetric Γ–A direction, but slightly far below the Fermi level. The results demonstrate BaSn3 as an excellent example hosting multiple Dirac fermions and an outstanding platform for studying the interplay between nontrivial topological states and superconductivity.