Instability of the Fermi surface in the one-dimensional Kondo lattice

The key parameters that characterize the long wavelength behaviour of correlation functions, including the Fermi momenta and the correlation length, are calculated using the transfer matrix renormalization group for the one-dimensional Kondo lattice model. The Fermi momentum varies slowly at high temperatures, but changes sharply at low temperatures in association with the formation of the Kondo singlets. By comparison with the temperature dependence of the conduction electron density, we find that the long wavelength correlations of conduction electrons are strongly affected by the localized spins at low temperatures. At high temperatures, the conduction electrons behave as for a system with a small Fermi surface. However, at low temperatures, the Fermi momentum of the conduction electrons is altered by the coupling with the localized spins.