Bosonization Approach to the One-Dimensional Kondo Lattice Model

The one-dimensional Kondo lattice model is investigated by using bosonization techniques and conformal field theory. In the half-filled band, the charge and spin gaps open for the anti-ferromagnetic Kondo coupling. Away from half-filling, the paramagnetic metallic state is characterized by the fixed point of Tomonaga-Luttinger liquid with the large Fermi surface in accordance with known results. It is suggested that as the electron density approaches half-filling, both of spin and charge susceptibilities may show a divergence property. 1 There is much current interest in the Kondo lattice model (KLM), which is considered to be a basic model for heavy fermion systems. The model hamiltonian consists of conduction electrons coupled with a localized spin array via the Kondo exchange interaction. The competition between the Kondo effect and the RKKY interaction results in various phases such as magnetic phases, Kondo insulators, etc. As a first step to understand the KLM, the one-dimensional (1D) KLM has been studied extensively by renormalization group methods 1,2, exact analytic methods 3, numerical diagonalizations 4,5, Monte Carlo simulations 6,7, and bosonization methods 8,9, which have clarified basic properties of the model. In this paper we investigate the low-energy physics of the 1D KLM by using bosonization and conformal field theory (CFT) techniques, and give complementary discussions to the results known so far. In particular, we point out that the marginally relevant spin interaction plays a key role in the model. We consider the 1D KLM, H = −t ∑ i,σ c † i,σci+1,σ + λK