Giant magnetoresistance in granular Fe-MgF2 films

The giant magnetoresistance effect observed in granular Fe-MgF2 films, which consist of metallic particles embedded in an insulating medium, is reported, Large negative magnetoresistance (MR) with a magnitude up to 7.5% at 78 K was observed in semiconducting films with the Fe composition below the percolation threshold, Field dependence of the MR is well described by the form proportional to the square of the magnetization. The MR effect in this system seems to arise from the tunneling conductance between the Fe particles depending on the relative relation of the magnetization direction. (C) 1996 American Institute of Physics.