Observation of a nondivergent Hall coefficient for a localized two-dimensional electron gas

We have studied the Hall coefficient for a two-dimensional electron gas in a GaAs/${\mathrm{Al}}_{\mathit{x}}$ ${\mathrm{Ga}}_{1\mathrm{-}\mathit{x}}$As heterojunction characterized by variable range hopping. We find the value of the Hall coefficient remains approximately classical, ${\mathit{R}}_{\mathit{H}}$=1/nec, for diverging longitudinal resistivity over a broad range of localization strength. The results show the behavior of a recently proposed Hall insulator in which ${\mathrm{\sigma }}_{\mathit{x}\mathit{x}}$→0, ${\mathrm{\sigma }}_{\mathit{x}\mathit{y}}$→0, and ${\mathrm{\rho }}_{\mathit{x}\mathit{x}}$→∞ but ${\mathrm{\rho }}_{\mathit{x}\mathit{y}}$→const for T→0.