Van Hemmen-Kondo model for disordered strongly correlated electron systems

Abstract

We present here a theoretical model in order to describe the competition between the Kondo effect and the spin glass behavior. The spin glass part of the starting Hamiltonian contains Ising spins with an intersite exchange interaction given by the local van Hemmen model, while the Kondo effect is described as usual by the intrasite exchange ${J}_{K}$. We obtain, for large ${J}_{K}$ values, a Kondo phase and, for smaller ${J}_{K}$ values, a succession, with decreasing temperature, of a spin glass phase, a mixed spin glass-ferromagnetic one and finally a ferromagnetic phase. This model improves the theoretical description of disordered Kondo systems with respect to previous models and can account for experimental data in Cerium disordered systems such as ${\text{CeCu}}_{1\ensuremath{-}x}{\text{Ni}}_{x}$ alloys.