Observation of the quantized Hall insulator in the quantum critical regime of the two-dimensional electron gas

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We have investigated the Hall resistance Rₕ near the plateau-insulator transition of a two-dimensional electron gas in the quantum critical regime. High-field magnetotransport data taken on a low-mobility InGaAs/InP heterostructure with the plateau-insulator transition at a critical field Bc of 17.2 T show that the Hall resistance Rₕ is quantized at h/e² near the critical filling fraction (νc = 0.55) when T → 0. By making use of universal scaling functions extracted from the magnetotransport data we show that Rₕ in the insulating phase in the limit T → 0 is quantized at h/e² for all values of the scaling parameter Δν/(T/T₀)κ with Δν= ν- νc. However, as a function of Δν (or magnetic field) the Hall resistance diverges in the limit T → 0 for all values ν< νc.