Temperature-driven 5 <i>f</i> localized-itinerant crossover and Dirac fermions in PuCoGa ₅

PuCoGa₅has attracted significant attention due to its record-breaking superconducting transition temperatureTc(≈ 18.5 K) among known<i>f</i>electron superconductors. We present a comprehensive investigation of the temperature-driven evolution of the electronic structure in the heavy-fermion superconductor PuCoGa₅using dynamical mean-field theory combined with density functional theory (DFT). Our calculations reproduce key features of experimental photoemission spectroscopy and reveal a pronounced crossover of Pu-5<i>f</i>electrons from localized states at high temperatures to itinerant, coherent heavy quasiparticles at low temperatures. This crossover is unequivocally evidenced by the emergence of a sharp Kondo resonance peak near the Fermi level, a large Fermi surface expansion, and a coherence temperature of 580 K extracted from the electron self-energy functions. Furthermore, we identify a symmetry-protected, fourfold degenerate Dirac node, originating from the<i>s</i>-<i>p_z</i>orbital crossing of Ga electrons. Notably, this Dirac fermion remains robust against strong correlations and temperature-dependent energy shifts, coexisting with the emergent coherent 5<i>f</i>states. Our work underscores PuCoGa₅as a unique platform where intertwined topology, strong correlations, and valence fluctuations lead to rich quantum phenomena.