Giant magnetoresistance in magnetic granular systems

Using a simple model of concentrically coated magnetic granules embedded in a nonmagnetic matrix, we analytically investigated properties in systems o f ellipsoidal magnetic granules. It is shown that giant magnetoresistance ( GMR) as well as the resistivities of these systems depend strongly on the s ize and shape of the granules. In particular, there is always an optimum gr ain size for the magnetoresistance. (C) 2000 Elsevier Science B.V. All righ ts reserved.