Magnetic impurity in correlated electrons system

TL;DR

This study investigates a magnetic impurity in a one-dimensional correlated electron system using the density-matrix renormalization group, revealing how binding energy and correlations vary with interaction strength and doping.

Contribution

It provides detailed analysis of impurity effects in the Hubbard model, including the behavior of binding energy and spin correlations across different regimes.

Findings

Binding energy increases exponentially in weak coupling

Spin-spin correlation decays exponentially with distance

Doping causes a discontinuous reduction in binding energy

Abstract

We study a magnetic impurity embedded in a correlated electron system using the density-matrix renormalization group method. The correlated electron system is described by the one-dimensional Hubbard model. At half filling, we confirm that the binding energy of the singlet bound state increases exponentially in the weak-coupling regime and decreases inversely proportional to the correlation in the strong-coupling regime. The spin-spin correlation shows an exponential decay with distance from the impurity site. The correlation length becomes smaller with increasing the correlation strength. We find discontinuous reduction of the binding energy and of spin-spin correlations with hole doping. The binding energy is reduced by hole doping; however, it remains of the same order of magnitude as for the half-filled case.