Phase diagram and skyrmion energy for bilayer heterostructures at integer filling factors

The phase diagram of a bilayer heterostructure at integer filling factors w as established using the hidden symmetry method. Three phases, namely, ferr omagnetic, canted antiferromagnetic (CAP), and spin-singlet, were found. We confirm early results of Das Sarma et al. Each phase violates the SU(4) hi dden symmetry and is stabilized by anisotropy interactions. A charged excit ation in the bilayer, i.e., a skyrmion, was found and its anisotropic energ y gap was calculated. The gap has a prominent minimum in the CAP. (C) 2000 MAIK "Nauka/Interperiodica".