We report on the results of experiments indicating the existence of the anomalous Hall effect associated with the ferromagnetic ordering of spins of localized holes in GaAs-AlGaAs quantum wells doped with shallow (Be) acceptors with the impurity concentration close to the metal-insulator transition at low temperatures. In insulator samples, an anomalous temperature dependence of the Hall mobility, an anomalous behavior of the Hall effect, magnetoresistance, and magnetic moments as functions of the magnetic field and temperature have been observed experimentally. On the other hand, in the samples on the metal side of the transition, the behavior typical of weak localization has been observed. The anomalous magnetotransport is explained by the emergence of a ferromagnetic transition or spin glass, which in turn is associated with the indirect spin exchange for strongly localized holes via delocalized states near the center of the impurity band.
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