Ginzburg-Landau functional for nearly antiferromagnetic perfect and disordered Kondo lattices

Interplay between Kondo effect and antiferromagnetic and spin glass ordering in perfect and disordered bipartite Kondo lattices is considered. The Ginzburg-Landau equation is derived from the microscopic effective action written in three mode representation (Kondo screening, antiferromagnetic correlations, and spin liquid correlations). The problem of the local constraint is resolved by means of the Popov-Fedotov representation of the localized spin operators. It is shown that the Kondo screening enhances the tendency to a spin-liquid crossover and partially suppresses antiferromagnetic ordering in perfect Kondo lattices and spin glass ordering in doped Kondo lattices. The modified Doniach diagram is constructed, and possibilities of going beyond the mean-field approximation are discussed.