Collapse of edge reconstruction in compressible quantum Hall fluid within filling fraction range 2/3 to 1

The edge structure of a gate-defined compressible quantum Hall fluid in the filling fraction range 2/3 to 1 is studied using the three reconstructed e2/3h fractional edge modes of a unity filling integer quantum Hall state. We find that the individually excited partially resolved e2/3h edge modes of the bulk state equilibrate completely even at higher magnetic field when passing through the gate-defined compressible fluid with filling between 2/3 and 1. This result is unexpected because edge reconstruction at the smooth boundary is generally expected due to dominant incompressibility at filling 2/3 and 1/3. Recently, such a reconstructed edge mode has been reported for the compressible fluid in the filling fraction range 1/3 to 2/3. In contrast, equilibration of fractional edge modes in the compressible fluid within the filling fraction range 2/3 to 1 becomes faster with increasing magnetic field. This anomalous result will stimulate further investigations on edge structure in these complex many-body systems.