Aperiodic exchange modulation effect on the specific heat in the Kondo necklace model

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Cuba-Supanta G.
Espinoza-Bernardo R.M.
Landauro C.V.
Reyes D.
Tarazona H.S.
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Elsevier B.V.
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In the present work we study the effect of the aperiodic exchange modulation on the spin gap at finite temperature as well as the specific heat of the Kondo necklace model in two and three dimensions. For this purpose, we use a representation for the localized and conduction electrons in terms of local Kondo singlet and triplet operators. A decoupling scheme on the double time Green’s functions is also used to find the dispersion relation for the excitations of the system. The influence of the aperiodic exchange modulation on the spin gap at low temperatures is discussed in the paramagnetic phase. Moreover, we investigate the specific heat as a function of the aperiodic exchange modulation at low temperatures in two cases: above the quantum critical point i.e., along the so-called non-Fermi liquid trajectory and in the Kondo spin liquid state. We have also compared our results with previous bond operator mean-field calculations.
D. R. would like to thank the Condensed Matter Research Group of San Marcos University, where part of this work was performed. G. C. -S., H. S. T., and R. M. E. -B. are grateful to National Council of Science and Technology (CONCYTEC) from Peru for the financial support through the Doctoral Program for Peruvian Universities (Nro 218–2014-CONCYTEC). C. V. L. and D. R. are grateful to the Programa Nacional de Innovación para la Competitividad y Productividad of the Peruvian Agency Innovate Perú for financial support under contract number Nro. 457-PNICP-ECIP-2015. C. V. L. would also like to thanks the San Marcos University for partial financial support under project number B17130021.
Palabras clave
Spin liquid state, Fermi liquids, Modulation, Quantum theory, Conduction electrons, Dispersion relations, Finite temperatures, Mean-field calculations, Modulation effects, Paramagnetic phase, Quantum critical points, Specific heat