We construct an effective Hamiltonian for bilayer quantum Hall ferromagnets, where the SU(4) nonlinear sigma model supports the SU(4) quantum coherence. At ν = 1 there are three independent soft waves and three basic skyrmions. At ν = 2 there exist two phases in each of which there are one soft wave and one biskyrmion. Interlayer tunneling occurs via the pseudospin soft mode not only at ν = 1 but also at ν = 2. © 2002 Elsevier Science B.V. All rights reserved.
Ezawa, Z. F., Hasebe, K., & Sawada, A. (2002). SU(4) quantum coherence and interlayer tunneling in bilayer quantum Hall systems. Physica E: Low-Dimensional Systems and Nanostructures, 12(1–4), 24–27. https://doi.org/10.1016/S1386-9477(01)00298-3