Interacting Dirac semi-metal state in nonsymmorphic Kondo-lattice compound CeAgSb₂

Abstract Dirac node-line (DNL) materials constitute a distinct category of topological semimetals, defined by the linear crossing of valence and conduction bands along one-dimensional lines within the Brillouin zone (BZ), resembling the behavior of Dirac fermions. However, spin–orbit coupling (SOC) and electronic interactions can typically alter these intersections and break the DNLs. In mostly reported cases, DNLs are classified as non-interacting types, which highlights the significant research value in searching for robust interacting DNLs in practical materials. Here, by employing first-principles calculations that combine density functional theory (DFT) with dynamical mean-field theory (DMFT), and leveraging symmetry-based indicator theory, we identify CeAgSb 2 as a Dirac semimetal. Our investigation reveals that robust Dirac nodal lines (DNLs) in this Kondo system are driven by Kondo interactions and nonsymmorphic lattice symmetries. Furthermore, our results demonstrate that the properties of these DNLs are substantially modulated by Kondo behavior across varying temperature regimes. The interacting DNLs in CeAgSb 2 represents a rare example of Dirac semimetal under electronic correlations, and the peculiar variation of Dirac fermions with temperature provides theoretical reference for future experimental explorations of novel electronic-correlation effects in topological materials.