Topological Excitations and their Contribution to Quantum Criticality in 2+1 D Antiferromagnets

TL;DR

This paper investigates the role of topological excitations, specifically skyrmions and topolons, in the quantum critical behavior of 2+1 D antiferromagnets, revealing their stability and impact on critical exponents.

Contribution

It introduces the concept of topolons as exact solutions combining skyrmions and antiskyrmions, and incorporates them into the quantum critical analysis of antiferromagnets.

Findings

Skyrmions are stable at criticality and persist at low temperatures.

The derived critical exponents are nu=0.9297 and eta=0.3381.

Topolons significantly influence the quantum critical properties.

Abstract

It has been proposed that there are new degrees of freedom intrinsic to quantum critical points that contribute to quantum critical physics. We study 2+1 D antiferromagnets in order to explore possible new quantum critical physics arising from nontrivial topological effects. We show that skyrmion excitations are stable at criticality and have nonzero probability at arbitrarily low temperatures. To include quantum critical skyrmion effects, we find a class of exact solutions composed of skyrmion and antiskyrmion superpositions, which we call topolons. We include the topolons in the partition function and renormalize by integrating out small size topolons and short wavelength spin waves. We obtain a correlation length critical exponent nu=0.9297 and anomalous dimension eta=0.3381.