Magnetotransport of a two-dimensional electron gas in a spatially random magnetic field

We study magnetotransport of a two-dimensional electron gas (2DEG) subject to a random magnetic field produced by a demagnetized NdFeB magnet. A large, positive, ssV-shaped magnetoresistance is observed in a perpendicular applied external field. This effect is interpreted classically in terms of a nonuniform local Hall resistivity. Depleting the 2DEG with a gate beneath the random magnet yields a crossover from positive to negative magnetoresistance at a sheet resistance ∼h/${\mathit{e}}^2$.