Tunneling giant magnetoresistance in coevaporated Fex(SiO)1-x thin films

Fe-x(SiO)(1-x) thin films, with volume fraction x ranging from 0.04 to 0.6, have been prepared by coevaporation. Magnetization, resistivity, and magnetoresistance measurements show that the behavior of this composite is metallic like for x greater than or equal to0.35. For 0.2 less than or equal tox less than or equal to0.27, the confrontation of all measurements prove the existence of a tunneling giant magnetoresistance between ferromagnetic grains at T < 300 K, where the mean radius of the grains is estimated to be about 1 nm. (C) 2000 American Institute of Physics. [S0021-8979(00)05923-5].