Electrostatic screening and experimental evidence of a topological phase transition in a bulk quantum Hall liquid

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The electrostatic screening in quantum Hall liquid was investigated by means of original electric field penetration (EFP) technique. At low temperatures and at magnetic fields corresponding to Hall regime with even filling factors a phase transition of Kosterlitz-Thouless’ type between two topologically different phases of electron liquid were identified.

 

Density of states in quantum Hall regime
Description
Dependence of effective density of electron states in quantum well (GaAs/GaAlAs, filling factor 2) on magnetic field for two different temperatures. The flat parts of the curves prove the existence of 1D electron liquid in the system. The arrows indicate the edges of quantum Hall plateau.