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

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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 Tₖ=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.