Susceptibility of a Magnetic Impurity in Two-Dimensional Disordered Electron Systems

TL;DR

This study uses quantum Monte Carlo simulations to explore how disorder affects the Kondo effect in two-dimensional electron systems, revealing position-dependent screening, a broad distribution of Kondo temperatures, and non-Fermi-liquid behavior at strong disorder.

Contribution

It provides new insights into the impact of disorder on Kondo screening and the distribution of Kondo temperatures in 2D disordered electron systems.

Findings

Kondo temperature varies with impurity position

Distribution of Kondo temperatures widens with disorder

Weak power-law divergence of susceptibility at low T

Abstract

We investigate the Kondo effect in two-dimensional disordered electron systems using a finite-temperature quantum Monte Carlo method. Depending on the position of a magnetic impurity, the local moment is screened or unscreened by the spin of the conduction electron. The results suggest that the Kondo temperature takes different values depending on the position of a magnetic impurity. We show that the distribution of the Kondo temperature becomes wide and the weight at $T_K=0$ becomes large as randomness increases. The average susceptibility shows a weak power-law divergence at low temperature in strongly disordered systems, indicating a non-Fermi-liquid behavior. We calculate the correlation function between the local moment and the spin of the conduction electron. The results are discussed in connection with Kondo screening.