Quantum critical behavior of the Kondo necklace model with aperiodic exchange modulation

The low energy behavior of the Kondo necklace model with an aperiodic exchange modulation is studied using a representation for the localized and conduction electron spins, in terms of local Kondo singlet and triplet operators at zero and finite temperature for arbitrary d dimensions. A decoupling scheme on the double time Green's functions is used to find the dispersion relation for the excitations of the system. We determined the dependence between the chemical aperiodic exchange modulation and the spin gap in 1d, 2d and 3d, at zero temperature and in the paramagnetic side of the phase diagram. On the other hand, at low but finite temperatures, the line of Nel transitions in the antiferromagnetic phase is calculated in function of the aperiodic exchange modulation. © 2010 Elsevier B.V. All rights reserved.