Magnetization process of one-dimensional Kondo necklace model with next-nearest-neighbor interaction

The magnetization process of one-dimensional Kondo necklace with next-nearest-neighbour interaction has been studied by the use of exact-diagonalization method. The magnetization plateaus appear at zero (m=0) and at half (m=1/2) of the saturation magnetization. The ground state in the absence of a magnetic field is regarded as an aggregate of intra-atomic Kondo singlets. On the other hand, the spin configuration at the 1/2-plateau represents the intra-chain dimer (sigma -dimer) phase with broken translational symmetry. The picture for spin configurations in the uniform magnetic fields other than m=0 and 1/2 are also given. We also determined the phase diagram for the ground state of the system in the magnetic field.