Skyrmions and Quantum Hall Ferromagnets in Improved Composite-Boson Theory

TL;DR

This paper introduces an improved composite-boson theory for quantum Hall ferromagnets, effectively describing excitations like Skyrmions and Goldstone modes, and matches experimental activation energy data.

Contribution

It develops a new composite-boson framework tightly linked to microscopic wave functions, enabling detailed analysis of topological excitations in quantum Hall systems.

Findings

Derivation of classical Skyrmion configurations from microscopic wave functions

Accurate estimation of Skyrmion activation energy

Effective description of Goldstone modes and topological solitons

Abstract

An improved composite-boson theory of quantum Hall ferromagnets is proposed. It is tightly related with the microscopic wave-function theory. The characteristic feature is that the field operator describes solely the physical degrees of freedom representing the deviation from the ground state. It presents a powerful tool to analyze excited states within the \LLLd. Excitations include a Goldstone mode and nonlocal topological solitons. Solitons are vortices and Skyrmions carrying the U(1) and SU(2) topological charges, respectively. Their classical configurations are derived from their microscopic wave functions. The activation energy of one Skyrmion is estimated, which explains experimental data remarkably well.