Structural and magnetic properties of Fe-Al2O3 films

We report a study on the structural and magnetic changes of Fe-Al2O3 films co-deposited at room temperature and subsequently annealed at 400 degreesC during 5 h. It is found that the annealing produces a better interface between the Fe clusters and the Al2O3 matrix, giving an increase in the magnetoresistance (MR) effect. Interesting is the bias dependence of MR. For low bias, below 2.5 V, the MR is negative and becomes positive for bias above 2.5 V. This effect can be ascribed to an inversion of the spin of tunneling electrons. (C) 2001 Elsevier Science B.V. All rights reserved.