Universal alternating order around impurities in antiferromagnets

TL;DR

This paper demonstrates a universal, temperature-independent pattern of alternating magnetic moments around vacancies in antiferromagnets, confirmed by quantum Monte Carlo simulations, with implications for experimental measurements.

Contribution

It introduces a universal expression describing impurity-induced magnetic order in antiferromagnets, valid across different materials and unaffected by quantum fluctuations.

Findings

Universal alternating magnetic order around vacancies

Expression valid over a wide temperature range

Quantum Monte Carlo confirms universality

Abstract

The study of impurities in antiferromagnets is of considerable interest in condensed matter physics. In this paper we address the elementary question of the effect of vacancies on the orientation of the surrounding magnetic moments in an antiferromagnet. In the presence of a magnetic field, alternating magnetic moments are induced, which can be described by a universal expression that is valid in any ordered antiferromagnet and turns out to be independent of temperature over a large range. The universality is not destroyed by quantum fluctuation, which is demonstrated by quantum Monte Carlo simulations in the two-dimensional Heisenberg antiferromagnet. Physical predictions for finite doping are made, which are relevant for experiments probing Knight shifts and the order parameter.