Temperature-driven 5flocalized-itinerant crossover and Dirac fermions in PuCoGa₅

Area of Science:

• Condensed Matter Physics
• Quantum Materials Science
• Superconductivity Research

Background:

• PuCoGa5 is a notable f electron superconductor with a record transition temperature (Tc ≈ 18.5 K).
• Understanding the electronic structure evolution in PuCoGa5 is key to explaining its superconducting properties.
• Heavy-fermion behavior and its interplay with electronic correlations are central to PuCoGa5 research.

Purpose of the Study:

• To investigate the temperature-driven evolution of the electronic structure in PuCoGa5.
• To elucidate the transition of Pu-5f electrons from localized to itinerant states.
• To identify the role of topology and strong correlations in PuCoGa5's quantum phenomena.

Main Methods:

• Combining Density Functional Theory (DFT) with Dynamical Mean-Field Theory (DMFT) for comprehensive electronic structure calculations.
• Analyzing temperature-dependent electronic properties and comparing with experimental photoemission spectroscopy data.
• Extracting coherence temperature and identifying topological features from electron self-energy functions.

Main Results:

• A pronounced crossover of Pu-5f electrons from localized to itinerant, coherent heavy quasiparticles was observed with decreasing temperature.
• Evidence for this crossover includes a Kondo resonance peak, Fermi surface expansion, and a coherence temperature of 580 K.
• A robust, symmetry-protected Dirac node was identified, originating from Ga electron orbital crossings, coexisting with the heavy 5f states.

Conclusions:

• PuCoGa5 showcases a unique platform where strong correlations, valence fluctuations, and topology drive complex quantum phenomena.
• The temperature-driven electronic structure evolution is critical for understanding its high-Tc superconductivity.
• The coexistence of topological Dirac fermions and heavy quasiparticles highlights PuCoGa5's potential for novel quantum effects.