An Intermediate Phase at the Metal-Insulator Boundary in a Magnetically Doped Two-Dimensional Electron System

A magnetotransport study in magnetically doped (Cd,Mn)Te 2D quantum wells reveals an apparent metal-insulator transition as well as an anomalous intermediate phase just on its metallic side. This phase is characterized by colossal magnetoresistance-like phenomena, which are assigned to the phase separation of the electron fluid and the associated emergence of ferromagnetic bubbles.