Transition metal driven altermagnetism and spin-orbit coupling effect in tetragonal Ce-based pnictides: a first-principles investigation.

We present a first-principles density functional theory (DFT) investigation of the structural, electronic and magnetic properties of the tetragonal CeX2Y2 (X = Co, Ni, and Fe; Y = P, As, and Sb) compounds, crystallizing in the ThCr2Si2-type structure (space group I4/mmm). Electronic properties of the relaxed structure are analyzed, highlighting the influence of Ce-4f and Co-3d states on the magnetic behaviour. The studies reveal that the Fe and Ni based compounds exhibit weak magnetism, and the Co-based compounds follow interlayer antiferromagnetic behaviour. The calculated density of states reveals a significant contribution from Ce-4f and Co-3d orbitals near the Fermi level (E F), indicating a complex interplay between localized and itinerant electronic states. The results further suggest the potential realization of altermagnetism arising from the magnetic structure of the CeCo2P2, showing d-wave like band splitting in the band structure and four lobe structure in the Fermi surface picture. Inclusion of spin-orbit coupling (SOC) leads to noticeable band splitting and modification of the near-Fermi-level band dispersion, which is relevant for understanding relativistic effects in Ce-based intermetallic compounds. These results provide a reliable computational baseline for further investigations of magnetism and possible topological features in CeX2Y2 and related materials. The present study serves as a starting point toward exploring correlation-driven and spin-orbit-induced phenomena in Ce-based pnictides.