Elementary Excitations of Quantum Critical 2+1 D Antiferromagnets

TL;DR

This paper demonstrates that skyrmion excitations are stable and fundamental at the quantum critical point of 2+1 D antiferromagnets, providing exact solutions and critical exponents that enhance understanding of quantum critical phenomena.

Contribution

It identifies skyrmion excitations as the critical degrees of freedom and introduces topolons, exact skyrmion-antiskyrmion solutions, into the analysis of quantum criticality.

Findings

Skyrmions are stable at the quantum critical point.

Exact solutions called topolons are constructed.

Critical exponents are calculated: nu=0.9297, eta=0.3381.

Abstract

It has been proposed that there are degrees of freedom intrinsic to quantum critical points that can contribute to quantum critical physics. We point out that this conclusion is quite general below the upper critical dimension. We show that in 2+1 D antiferromagnets skyrmion excitations are stable at criticality and identify them as the critical excitations. We found 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 correlation length exponent nu=0.9297 and anomalous dimension eta=0.3381.