Fig. 1. Structure and phonon spectrum of NbIrTe₄. (a) Side view of NbIrTe₄ crystal structure, with purple, yellow, and green spheres representing Nb, Te, and Ir atoms, respectively; (b) polyhedral representation of NbIrTe₄ crystal structure; (c) Brillouin zone of NbIrTe₄; (d) phonon spectrum of NbIrTe₄

Fig. 2. Energy-band structure of NbIrTe₄. (a)(b) Energy-band structure without considering SOC and zoomed-in views along high-symmetry paths Γ→X and Γ→Z, respectively; (c)(d) energy-band structure with consideration of SOC and zoomed-in view along high-symmetry path Γ→X

Fig. 3. Electronic structure of NbIrTe₄ with contributions from atomic orbitals. (a) Energy-band structure of NbIrTe₄; (b) partial density of states for NbIrTe₄ with consideration of SOC

Fig. 4. Calculated results of Fermi arcs on the (001) plane of NbIrTe₄. (a) Top surface; (b) bottom surface

Fig. 5. Surface state spectra of NbIrTe₄ on (001) plane. (a) Fermi surface of bulk NbIrTe₄ at k_z=0, four Weyl points on this plane denote by green circles; (b) top surface state spectrum of NbIrTe₄ on (001) plane along S¯→Y¯→S¯ path; (c)(d) top surface state spectrum of NbIrTe₄ on (001) plane along X¯→Γ¯→X¯ path and the detailed zoomed-in spectrum, with emphasis on the locations of Weyl points (green cross symbols) and Fermi arcs (green dashed lines); (e) top surface state spectrum of NbIrTe₄ on the (001) plane along Y¯→Γ¯→Y¯ path; (f) bottom surface state spectrum of NbIrTe₄ on the (001) plane along Y¯→Γ¯→Y¯ path

Fig. 6. Spectra of all symmetry-allowed components of conductivity tensor of displacement current for NbIrTe₄