Generalized Kondo lattice model and its spin-polaron realization by the projection method for cuprates

The spin–fermion model, which is an effective low-energy realization of the three-band Emery model after passing to the Wannier representation for the p_x and p_y orbitals of the subsystem of oxygen ions, reduces to the generalized Kondo lattice model. A specific feature of this model is the existence of spin-correlated hoppings of the current carriers between distant cells. Numerical calculations of the spectrum of spin-electron excitations highlight the important role of the long-range spin-correlated hoppings.