Evolution of a Large Fermi Surface in the Kondo Lattice

The single-particle spectrum of the Kondo lattice model is derived with the use of the continuous-time quantum Monte Carlo method, combined with the dynamical mean-field theory. Crossover behavior is traced quantitatively either to a heavy Fermi-liquid state or to a magnetically ordered state from the local-moment state at high temperatures. The momentum distribution in the low-temperature limit acquires a discontinuity at the location that involves the local-spin degrees of freedom. Even without the charge degrees of freedom for local electrons, the excitation spectra exhibit hybridized bands similar to those in the Anderson lattice. Temperature dependence in the zero-energy component of the self-energy is crucial in forming the Fermi-liquid state with the large Fermi surface.

Figure 1

The phase diagram of the KLM at $n_c=0.9$. The intensity map represents $\xi$ defined by Eq. (6), and the coherent energy scale $T^{*}$ is defined by $\xi =0.5$.

Figure 2

The single-particle excitation spectrum $A(\kappa ,\omega )$ for $J=0.3$ and $n_c=0.9$ at (a) $T=0.25$ and (b) $T=0.0025$. The slanted line represents the noninteracting spectrum $\omega =\kappa -\mu$ which is realized with $J=0$.

Figure 3

Temperature dependences of the chemical potential $\mu$ and its self-energy correction $\mu -\mathrm{Re}{\Sigma }_c(0)$ for $n_c=0.9$.

Figure 4

Momentum distribution $n_c(\kappa )$ for $J=0.3$ and $n_c=0.9$. The vicinity of the large Fermi surface is enlarged in the left inset. The right inset shows the temperature dependences of the “width” of $n_c(\kappa )$ at $\kappa ={\kappa }_S$ and ${\kappa }_L$.