Transport evidence for phase separation into spatial regions of different fractional quantum Hall fluids near the boundary of a two-dimensional electron gas.

Abstract

Near the boundary, a 2D electron gas can phase separate into fractional quantum Hall fluid regions of successively lower filling factors (ν), in the case of a slowly increasing boundary potential. We present experimental evidence in the ν=1/3, 2/3, and 1 quantum Hall regimes on a four-lead Hall junction showing that by side gating the junction boundary, the Hall resistance can be made to approach the quantized value of the lower ν fluids in the top-gated leads, rather than the higher-ν fluid at the junction center. This implies the presence of the lower-ν fluids near the junction boundary