ROLE OF ELECTRON LAKES IN THE NEGATIVE MAGNETORESISTANCE EFFECT IN THE REGION OF MOTT HOPPING CONDUCTIVITY

It is shown for doped and compensated germanium that the appearance of negative magnetoresistance under the conditions of Mott hopping condu ctivity may be due to the presence of a nonuniform spatial distributio n of the electron density, the temperature at which the effect appears apparently being determined by the temperature at which the electron gas condenses into electron ''lakes.'' A ''dead zone'' effect was also observed in weak magnetic fields, the threshold field increasing with the nonuniformity of the electron distribution. (C) 1996 American Ins titute of Physics.