de Haas–van Alphen Quantum Oscillations in BaSn_3 Superconductor with Multiple Dirac Fermions

Characterization of Fermi surface of the BaSn_3 superconductor (T_\rm c \sim 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 \varGamma–A direction, but slightly far below the Fermi level. The results demonstrate BaSn_3 as an excellent example hosting multiple Dirac fermions and an outstanding platform for studying the interplay between nontrivial topological states and superconductivity.