Local investigation of thin insulating barriers incorporated in magnetic tunnel junctions

In this work we study properties of very thin insulating Al oxide films, us ed as barriers in magnetic tunnel junctions. For the small barrier thicknes ses required for technological applications (similar to 10 Angstrom), the p resence of pinholes (direct contact between the ferromagnetic metals throug h the barrier), or oxidation inhomogeneities, are the major factors for van ishing of the tunnel magnetoresistance effect. We have produced and charact erized very thin, pinhole-free Al oxide layers, incorporated in magnetic tu nnel junctions. The transport properties of the different barriers were ana lyzed by barrier impedance scanning microscopy and were correlated with the magnetotransport properties of the patterned microsized junctions. (C) 200 1 American Institute of Physics.