One- and many-body effects on mirages in quantum corrals

TL;DR

This paper models the electronic and many-body effects in quantum corrals to understand the formation of quantum mirages, combining solutions of the Schrödinger equation with Anderson impurity models to match experimental observations.

Contribution

It introduces a detailed theoretical framework for soft-circular quantum corrals, incorporating many-body interactions and surface state Green's functions to predict mirage phenomena.

Findings

Reproduces main experimental features of quantum mirages

Analyzes the impact of corral size, potential, and temperature on mirage intensity

Calculates spin-spin correlations in the system

Abstract

Recent interesting experiments used scanning tunneling microscopy to study systems involving Kondo impurities in quantum corrals assembled on Cu or noble metal surfaces. The solution of the two-dimensional one-particle Schrodinger equation in a hard wall corral without impurity is useful to predict the conditions under which the Kondo effect can be projected to a remote location (the quantum mirage). To model a soft circular corral, we solve this equation under the potential W*delta(r-r0), where r is the distance to the center of the corral and r0 its radius. We expand the Green's function of electron surface states Gs0 for r<r0 as a discrete sum of contributions from single poles at energies epsilon_i-I*delta_i. The imaginary part delta_i is the half-width of the resonance produced by the soft confining potential, and turns out to be a simple increasing function of epsilon_i. In presence of an impurity, we solve the Anderson model at arbitrary temperatures using the resulting expression for Gs0 and perturbation theory up to second order in the Coulomb repulsion U. We calculate the resulting change in the differential conductance Delta dI/dV as a function of voltage and space, in circular and elliptical corrals, for different conditions, including those corresponding to recent experiments. The main features are reproduced. The role of the direct hybridization between impurity and bulk, the confinement potential, the size of the corral and temperature on the intensity of the mirage are analyzed. We also calculate spin-spin correlation functions.