Photo-emission signatures of coherence breakdown in Kondo alloys: dynamical mean-field theory approach

We study the Kondo alloy model on a square lattice using dynamical mean-field theory for Kondo substitution and disorder effects, together with static mean-field approximations. We computed and analyzed photoemission properties as a function of electronic filling n (c) , Kondo impurity concentration x, and strength of Kondo temperature T (K). We provide a complete description of the angle resolved photoemission spectroscopy (ARPES) signals expected in the paramagnetic (PM) Kondo phases. By analyzing the Fermi surface (FS), we observe the Lifshitz-like transition predicted previously for strong T (K) at x = n (c) and we discuss the evolution of the dispersion from the dense coherent to the dilute Kondo regimes. At smaller T (K), we find that this transition marking the breakdown of coherence at x = n (c) becomes a crossover. However, we identify another transition at a smaller concentration x(;) where the effective mass continuously vanishes. x separates the one-branch and the two-branches ARPES dispersions characterizing respectively dilute and dense Kondo PM regimes. The x - T (K) phase diagrams are also described, suggesting that the transition at x might be experimentally observable since magnetically ordered phases are stabilized at much lower T (K). FS reconstructions in antiferromagnetic and ferromagnetic phases are also discussed.