Spectroscopic evidence for Dirac nodal surfaces and nodal rings in the superconductor NaAlSi

The discovery of the topological states has become a key topic in condensed matter physics with focus evolving from Dirac or Weyl points to high-dimension nodal lines and surfaces. For material manifest its quantum properties useful applications, need be genuine clean so that they lie close Fermi level without other trivial bands existing at level. While number materials are predicted, only few them have been synthesized confirmed ones especially scarce. Here we report realization multiple NaAlSi. By performing high-resolution angle-resolved photoemission measurements band structure calculations, observed two sets surfaces formation homocentric ring rings distinct inner one is type-{\uppercase\expandafter{\romannumeral1}} while outer embedded four type-{\uppercase\expandafter{\romannumeral3}} points. All involved very no coexisting These observations make NaAlSi desirable explore for novel exotic properties.