Possible Jahn-Teller effect in Si inverse layers

The Jahn-Teller effect in a bivalley Si(100) heterostructure under conditions of the quantum Hall effect at integer filling factors ν=1, 2, and 3 is studied. This system is described by an SU(4) hidden symmetry. At ν=2 static and dynamic lattice deformations give rise to an easy-plane anisotropy and an antiferromagnetic exchange, and lift the valley degeneracy. At ν=1, and 3 Coulomb interaction is essential to produce a weak easy-plane anisotropy. At ν=2 three phases, ferromagnetic, canted antiferromagnetic, and spin-singlet, have been found. The anisotropy energy of charged skyrmion excitation in every phase is calculated.