Microscopic origin of local moments in a zinc-doped high-$T_{c}$ superconductor

TL;DR

This paper investigates the microscopic origin of local magnetic moments induced by zinc impurities in high-temperature cuprate superconductors using a bosonic RVB framework, revealing a topological basis and consistency with experimental data.

Contribution

It introduces a topological explanation for local moments around zinc impurities within the bosonic RVB theory of the $t-J$ model, linking impurity effects to the RVB nature of cuprates.

Findings

Local moments form near zinc impurities as staggered magnetic moments.

Calculated magnetic properties match experimental measurements.

Zinc substitution provides evidence for RVB physics in cuprates.

Abstract

The formation of a local moment around a zinc impurity in the high-$T_{c}$ cuprate superconductors is studied within the framework of the bosonic resonating-valence-bond (RVB) description of the $t-J$ model. A topological origin of the local moment has been shown based on the phase string effect in the bosonic RVB theory. It is found that such an $S=1/2$ moment distributes near the zinc in a form of staggered magnetic moments at the copper sites. The corresponding magnetic properties, including NMR spin relaxation rate, uniform spin susceptibility, and dynamic spin susceptibility, etc., calculated based on the theory, are consistent with the experimental measurements. Our work suggests that the zinc substitution in the cuprates provide an important experimental evidence for the RVB nature of local physics in the original (zinc free) state.