Modeling of the current lines in discontinuous metal/insulator multilayers

Discontinuous magnetic metal/insulator multilayers are formed of equally spaced layers of magnetic particles embedded in an insulating matrix. Their electronic transport properties result from spin-polarized electron tunneling and Coulomb blockade effect. The current-in-plane (CIP) and current-perpendicular-to plane (CPP) resistances change by several orders of magnitude when the thicknesses of the metallic or insulating layers are varied. Calculations of the shape of the current lines in these multilayers are presented. It is shown that pure CIP or CPP transport occur in these systems only when the CIP or CPP resistances are very different in magnitude. If the two resistances are of the same order of magnitude, then the measured transport properties in both geometries are a combination of CIP and CPP transport. Received 9 October 2001