Doping-induced perturbation and percolation in the two-dimensional Anderson lattice

TL;DR

This study uses quantum Monte Carlo simulations to analyze doping effects in a 2D Anderson lattice, revealing a percolation-driven insulator-metal transition and challenging previous mean-field predictions.

Contribution

It provides the first detailed numerical evidence linking doping-induced percolation to the insulator-metal transition in the 2D Anderson lattice.

Findings

Bound states form around Kondo holes.

Heavy electron states are destroyed near doping sites.

Critical doping x_c~0.6 marks a transition consistent with site percolation.

Abstract

We examine the doping effects in the two-dimensional periodic Anderson model using the determinant Quantum Monte Carlo (DQMC) method. We observe bound states around the Kondo hole site and find that the heavy electron states are destroyed at the nearest-neighbor sites. Our results show no clear sign of hybridization oscillation predicted in previous mean-field calculations. We further study the electron transport with increasing doping and as a function of temperature and obtain a critical doping at x_c~0.6 that marks a transition from the Kondo insulator regime to the single-ion Kondo regime. The value of x_c is in good agreement with the predicted threshold for the site percolation. Our results confirm the percolative nature of the insulator-metal transition observed in doped Kondo insulators.