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Antiferromagnetic and spin gap phases of the anisotropic Kondo necklace model

A. Langari·P. Thalmeier
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Abstract

We have studied the effect of anisotropies on the quantum phase transition of the Kondo necklace model in dimensions D=1, 2 and 3. Both the anisotropy $δ$ of the inter-site interaction term and anisotropy $Δ$ of the on-site Kondo interaction have been included. We use a bond operator method with constraints implemented in mean field approximation. Starting from the paramagnetic phase we determine the critical ratio $(t/J)_c$ of the quantum critical point and associated scaling exponents of the Kondo-singlet gap. We show that in the case of easy-axis type anisotropy $δ>1$ a qualitatively new behavior in comparison to the conventional Kondo necklace model with ($δ$,$Δ$)=(0,1) appears. We have also obtained the antiferromagnetic order parameter in the long range ordered phase for $t > t_c$.

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A. Langari, P. Thalmeier. 2006-06-30. Antiferromagnetic and spin gap phases of the anisotropic Kondo necklace model. https://doi.org/10.1103/physrevb.74.024431

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