Collapse of odd-integer Hall gaps in double quantum wells due to edge effects

We show, within the Hartree-Fock approximation, that the quantum Hall effect for total filling factor $\nu =1,3,5,$ and $7$ can be destroyed due to many-body effects induced by the edges of a bilayer system. For $\nu =1,$ we also study the correlation effects, in addition to the exchange interaction, which are mainly related to the edge-state screening. Calculation results explain quite well the experimental behavior observed in double-quantum-well structures with rather large tunnel splitting ${\Delta }_{\mathrm{SAS}}\gtrsim 0.5\mathrm{K}.$