Temperature-driven 5 f localized-itinerant crossover and Dirac fermions in PuCoGa 5

Abstract PuCoGa 5 has attracted significant attention due to its record-breaking superconducting transition temperature T c (≈ 18.5 K) among known f electron superconductors. We present a comprehensive investigation of the temperature-driven evolution of the electronic structure in the heavy-fermion superconductor PuCoGa 5 using 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 f 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 s - p z 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 f states. Our work underscores PuCoGa 5 as a unique platform where intertwined topology, strong correlations, and valence fluctuations lead to rich quantum phenomena.