why FQHE needs a lower energy state with gaped specrum

knightq

Hi, everyone. I have read some materials about fractional quantum hall effect,especially about Laughlin's wavefunction. However a lot of them claim Laughlin's wave function have lower energy and a gap in spectrum but seldom explain why that could explain the plateau. Also from my observation, it's not like phase transition, which was the first thing across my mind when I see "lower energy", since the energy at v=1/3 is lower than energy at different filling factors not, the energy of a "normal state" at the same v=1/3.
If anyone is a expert in this field , could you explain to me why a lower energy state at v=1/3 with gaped spectrum could explain the plateau? Thanks