SPIN-POLARIZED TUNNELING IN FERROMAGNET INSULATOR FERROMAGNET JUNCTIONS

Experimental data and theoretical explanation reported for spin polari zed tunneling in ferromagnet/insulator/ferromagnet are reviewed. The m agnetoresistance (MR) ratio due to the spin polarized tunneling is rel atively smaller value than that of giant magnetoresistance in artifici al superlattices. However, recent results reported by us are an order of magnitude larger than those reported in the past. We demonstrate th at the magnetoresistance ratio is roughly proportional to the product of spin polarizations of both ferromagnets. The dependence of MR ratio , saturation resistance and conductance on temperature are also discus sed.