Impurity induced spin texture in quantum critical 2D antiferromagnets

TL;DR

This paper investigates how a vacancy affects local magnetization in a quantum critical 2D antiferromagnet, revealing a universal spin texture influenced by Berry phases, supported by large-scale quantum Monte Carlo simulations.

Contribution

It introduces a universal functional form for impurity-induced spin textures in quantum critical 2D antiferromagnets, supported by extensive numerical simulations and analysis.

Findings

Universal spin texture form due to Berry phase effects

Determined critical exponent eta' = 0.40 +/- 0.02

Good agreement between simulations and theoretical scaling

Abstract

We describe the uniform and staggered magnetization distributions around a vacancy in a quantum critical two-dimensional S=1/2 antiferromagnet. The distributions are delocalized across the entire sample with a universal functional form arising from an uncompensated Berry phase. The numerical results, obtained using quantum Monte Carlo simulations of the Heisenberg model on bilayer lattices with up to approximately 10^5 spins, are in good agreement with the proposed scaling structure. We determine the exponent eta'=0.40 +/- 0.02, which governs both the staggered and uniform magnetic structure away from the impurity and also controls the impurity spin dynamics.