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.
Bibliographical noteFunding Information:
D. Reyes would like to thank the Brazilian MCT for financial support and would also like to thank the Condensed Matter Research Group of San Marcos University for the hospitality and the stimulating intellectual atmosphere. We are indebted to Nils Hasselmann for reading the manuscript and numerous valuable critical comments.
Copyright 2011 Elsevier B.V., All rights reserved.
- Aperiodic modulation
- Heavy fermions
- Quantum phase transition