Dynamic localization of two-dimensional electrons at mesoscopic length scales

We have investigated the local magnetotransport in high quality two-dimensional electron systems at low carrier densities. The positive magnetoresistance in perpendicular magnetic field in the strongly insulating regime has been measured to evaluate the spatial concentration of electron trap sites within a mesoscopic region of the samples. A simultaneous measurement of the electron density within the same region shows an unexpected correspondence between the density of electrons in the metallic regime and that of the localizing sites in the insulating phase. We have shown this to imply a self-localized many-body ground state in the interacting regime, stabilized by optimal disorder.