Magnetotransport experiments on a low-disorder electron system in an 800 -wide GaAs quantum well reveal a dramatic evolution from a double- to a single-layer system as the electron density is decreased or the system is made asymmetric. At an intermediate density of 9.7×1010 cm-2, we observe fractional quantum Hall states at Landau level filling factors of ν=3/4, 1/2, and 1/3, with an insulating phase separating the ν=1/2 and 1/3 liquid states. Our data demonstrate that the ν=1/2 state and the insulating phase are most stable in symmetric double-layer systems with appropriate parameters while the ν=1/3 and 3/5 states have a single-layer origin.
All Science Journal Classification (ASJC) codes
- General Physics and Astronomy