Spinless impurities in high Tc cuprates: Kondo-like behavior

TL;DR

This paper investigates how non-magnetic impurities Li and Zn affect high-Tc cuprates, revealing universal spin perturbation effects and a Kondo-like behavior in the induced magnetic moments.

Contribution

It demonstrates that spinless impurities cause similar effects on cuprates, highlighting the dominant role of spin perturbations over charge defects and identifying a Kondo-like behavior.

Findings

Li does not localize extra holes in cuprates.

Zn and Li induce similar magnetic moments.

Induced moments follow a 1/(T+Theta) susceptibility, indicating Kondo-like behavior.

Abstract

We compare the effects of in-plane non magnetic Li$^{+}$ and Zn$^{2+}$ impurities on the normal state of high-T$_{c}$ cuprates. Y NMR shows that the extra hole introduced by Li is not localized in its vicinity. The Tc depression and induced moments on near neighbour Cu sites of Zn or Li are found identical. These universal effects of spinless impurities establish the major influence of the spin perturbation with respect to the charge defect. The susceptibility of the induced moment measured by Li NMR displays a 1/(T+Theta) behavior. Theta increases with doping up to about 200 K in the overdoped regime. We attribute this to a "Kondo like" effect.