Disordered Kondo nanoclusters: effect of energy spacing

Exact-diagonalization results for Kondo nanoclusters alloyed with mixed-valence impurities show that tuning the energy spacing D drives the system from the Kondo to the Ruderman-Kittel-Kasuya-Yosida (RKKY) regime. The interplay of D and disorder gives rise to a D versus concentration T=0 phase diagram very rich in structure. The parity of the total number of electrons alters the competition between the Kondo and RKKY correlations. The local Kondo temperatures TK and RKKY interactions depend strongly on the local environment and overall are enhanced by disorder, in contrast to the hypothesis of "Kondo disorder" single-impurity models.