Observation of superconductivity in a nontrivial $${{{{\mathcal{Z}}}}}_{2}$$ approximant quasicrystal

Superconductivity and nontrivial topology are highly sought-after phenomena in quantum materials. While many topological crystalline materials have been found to exhibit superconductivity, their presence in quasicrystals—materials with a unique aperiodic yet ordered structure—has remained largely unexplored. In this work, we report the discovery of superconductivity in a monoclinic approximant to the decagonal quasicrystal Al13Os4, that exhibits a high superconducting transition temperature and a nontrivial electronic structure. The resistivity, magnetization, specific heat, and μSR measurements confirm superconductivity with a critical temperature of ~5.47 K. Detailed electronic structure and symmetry analysis reveal nontrivial state with $${{{{\mathcal{Z}}}}}_{2}=1$$ and spin-polarized conducting surface states. Importantly, we identify three-dimensional saddle point van Hove singularities with substantial flat energy dispersion at the Fermi level, which can enhance superconductivity. Our results highlight a rich interplay between superconductivity and nontrivial electronic states in Al13Os4, demonstrating it as a unique platform for exploring unconventional superconducting states in quasicrystalline materials. The presence of superconductivity in quasicrystals is largely unexplored. Here, a high superconducting transition temperature and a nontrivial electronic structure are observed in a monoclinic approximant of a decagonal quasicrystal.