Spin-Pseudospin Coherence and CP$^{3}$ Skyrmions in Bilayer Quantum Hall Ferromagnets

TL;DR

This paper investigates the properties of bilayer quantum Hall ferromagnets with SU(4) symmetry, focusing on spin-pseudospin coherence, CP^3 skyrmions as quasiparticles, and their experimental implications.

Contribution

It introduces the concept of CP^3 skyrmions as quasiparticles in bilayer quantum Hall systems and analyzes their charge and coherence properties.

Findings

Spin-pseudospin coherence develops spontaneously at low electron densities.

Quasiparticles are identified as CP^3 skyrmions that induce charge modulations.

Charge of elementary excitations at filling factor 2/m is 2e/m, supported by experimental data.

Abstract

We analyze bilayer quantum Hall ferromagnets, whose underlying symmetry group is SU(4). Spin-pseudospin coherence develops spontaneously when the total electron density is low enough. Quasiparticles are CP^3 skyrmions. One skyrmion induces charge modulations on both of the two layers. At the filling factor$\nu =2/m$ one elementary excitation consists of a pair of skyrmions and its charge is $2e/m$. Recent experimental data due to Sawada et al. [Phys. Rev. Lett. {\bf 80}, 4534 (1998)] support this conclusion.