Charge excitation and transport in pseudospin quantum Hall ferromagnets

Studies on pseudospin quantum Hall ferromagnets involving the N=1 Landau level (LL) of the symmetric state and the N=0 LL of the antisymmetric state in strongly-coupled double quantum wells are presented. Measurements of the charge excitation gap for ν=4 (3 and 5) reveal easy-axis (easy-plane) anisotropy. Resistance spikes observed for ν=4 are ascribed to transport along domain walls. We also discuss the effects of potential asymmetry.