Enhancement of tunneling magnetoresistance through a magnetic barrier of granular Fe-Pb-O system

A large value of magnetoresistance ratio has been observed in granular Fe-Pb-O solids. The large MR value is associated with the appearance of magnetic Pb ferrite encapsulated on the surface of iron granules. Spin-dependent tunneling picture can qualitatively describe the enhancement of magnetoresistance ratio. Calculated results based on the spin filter effect of the Pb-ferrite layer are reasonably in agreement with the experimental data of TMR enhancement in Fe-Pb-O solids.