Fig. 1. Crystal and electronic structures of a nodal-line semimetal SrAs₃.

a The crystal structure of SrAs_3. b The schematic band crossing for asymmetric nodal-line states with a tilted energy dispersion (E_tilt), a finite spin–orbit-coupling gap (Δ_SOC) and a band overlap energy (Δ). The corresponding Fermi surfaces at different Fermi levels (E_F) are shown in the right, a crescent-type for E_F,1 and a torus-type for E_F,2. c The smoke-ring-type pseudospin texture imprinted on the Fermi surface. d The Brillouin zone of SrAs₃ with a single nodal ring (red circle) centered at the Y point. e The ARPES spectra of SrAs₃ taken at the Y point along k_x with the photon energy of 99 eV. The overlaid red and blue lines indicate the conduction and valence bands, respectively. f The temperature dependence of the in-plane resistivity (ρ). The inset shows the carrier densities (n) for electron (e) and hole (h). g The magnetic field-dependent Hall resistivity (ρ_xy) of SrAs₃ at different temperatures. h A series of ARPES spectra taken along k_x at different photon energies (85-104 eV) corresponding to k_y marked on top of each panel. i The nodal-ring of the crossing points between the conduction and valence bands in ARPES data, with dashed red circle as a guide to the eye.