Spin-Pseudospin Coherence andCP3Skyrmions in Bilayer Quantum Hall Ferromagnets

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. The quasiparticles are ${\mathrm{CP}}^3$ Skyrmions. One Skyrmion induces charge modulations on both layers. At the filling factor $\nu =2\mathrm{}/m$ 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. 80, 4534 (1998)] support this conclusion.