Realization of low-energy type-II Dirac fermions in (Ir1−xPtx)Te2 superconductors**Project supported by the Ministry of Science and Technology of China (Grant Nos. 2016YFA0300600, 2016YFA0401000, 2016YFA0302400, and 2017YFA0302901), the National Natural Science Foundation of China (Grant Nos. 11622435, U1832202, and 11674369), the Chinese Academy of Sciences (Grant Nos. QYZDB-SSW-SLH043, XDB07000000, and XDPB08-1), and the Beijing Municipal Science and Technology Commission, China (Grant

Abstract

Topological Dirac semimetals (DSMs) present a kind of topologically nontrivial quantum state of matter, which has massless Dirac fermions in the bulk and topologically protected states on certain surfaces. In superconducting DSMs, the effects of their nontrivial topology on superconducting pairing could realize topological superconductivity in the bulk or on the surface. As superconducting pairing takes place at the Fermi level EF, to make the effects possible, the Dirac points should lie in the vicinity of EF so that the topological electronic states can participate in the superconducting paring. Here, we show using angle-resolved photoelectron spectroscopy that in a series of (Ir1−xPtx)Te2 compounds, the type-II Dirac points reside around EF in the superconducting region, in which the bulk superconductivity has a maximum Tc of ∼ 3 K. The realization of the coexistence of bulk superconductivity and low-energy Dirac fermions in (Ir1−xPtx)Te2 paves the way for studying the effects of the nontrivial topology in DSMs on the superconducting state.