Three-dimensional electronic structure of the superconductor Sn4Sb3 by angle-resolved photoemission spectroscopy

The layered material Sn4Sb3 exhibits superconductivity with T c∽1.47 K and is proposed to be a topological superconductor candidate. In this study, we investigate the electronic structure of Sn4Sb3 using angle-resolved photoemission spectroscopy and density functional theory (DFT) calculations. Despite its layered structure, the band structure of Sn4Sb3 shows strong k z dependence, leading to the formation of a three-dimensional Fermi surface. The electronic bands exhibit three-fold symmetry at most k z planes and six-fold symmetry at the Γ and Z planes. These observations are consistent with DFT calculations, except for the presence of additional flat-like bands located 500 meV below the Fermi level. The photon energy dependence measurement show noticeable k z dispersion in one of the splitted branches, suggesting a bulk origin of the feature, and negligible k z dispersion in another branch, implying the surface origin of the state.