METASTABILITY OF THE QUANTUM HALL STATES IN ASYMMETRIC 2-LAYER SYSTEMS

A GaAs-AlxGa1-xAs asymmetric double-quantum-well structure exhibits a meta-stability in the quantum Hall regime when the system is illuminat ed, under a high magnetic field sufficient to depopulate the excited-s tate subband. The photo-generated electrons are transferred to the exc ited-state subband when its bottom Landau level falls below the Fermi level at lower magnetic fields. The metastability is attributed to the potential renormalization associated with the charge transfer. The am ount of the transferred charge can be controlled by varying the minimu m magnetic held and remains unchanged as long as the magnetic field st ays above the previous minimum value.