Kondo Lattice Model with Finite Temperature Lanczos Method

TL;DR

This study uses the Finite Temperature Lanczos Method to analyze the 2D Kondo Lattice Model, revealing how electron density of states influences the balance between Kondo screening and RKKY interactions across different boundary conditions.

Contribution

It provides a systematic analysis of thermodynamic and correlation functions at finite temperatures for the Kondo Lattice Model, highlighting the impact of electron density of states on competing interactions.

Findings

Two energy scales exist when states are near the Fermi level, associated with screening and RKKY.

The form of the electron density of states significantly affects the dominance of Kondo or RKKY interactions.

Different boundary conditions lead to distinct regimes depending on the electron states around the Fermi level.

Abstract

We investigate the Kondo Lattice Model on 2D clusters using the Finite Temperature Lanczos Method. The temperature dependence of thermodynamic and correlations functions are systematically studied for various Kondo couplings JK. The ground state value of the total local moment is presented as well. Finally, the phase diagrams of the finite clusters are constructed for periodic and open boundary conditions. For the two boundary conditions, two different regimes are found for small JK/t, depending on the distribution of non-interacting conduction electron states. If there are states within JK around the Fermi level, two energy scales, linear and quadratic in JK, exist. The former is associated with the onsite screening and the latter with the RKKY interaction. If there are no states within JK around the Fermi level, the only energy scale is that of the RKKY interaction. Our results imply that the form of the electron density of states (DOS) plays an important role in the competition between the Kondo screening and the RKKY interaction. The former is stronger if the DOS is larger around the Fermi level, while the latter is less sensitive to the form of the DOS.