Magnetic-field-induced triple-layer to bilayer transition

Magnetotransport measurements on a triple-layer electron system in a triple quantum well reveal a surprising transition to a bilayer system at high magnetic fields. This transition occurs in the extreme quantum limit, and is signaled by the appearance of strong fractional quantum Hall liquid states which are clearly characteristic of a bilayer system. We attribute the transition to a charge transfer from the center layer to the side layers, and argue that the associated Hartree (capacitive) energy cost is compensated by the correlation energy gained in forming two incompressible fractional quantum Hall liquid states in the side layers.