Spin-valve-like properties of ferromagnetic tunnel junctions

Ferromagnetic tunnel junctions with naturally oxidized Al barriers were fabricated by magnetron sputtering. Using metal masks, 0.01 mm(2) junction areas were patterned. Junctions with slightly oxidized Al barriers showed small tunnel resistances. Of those, some had extraordinarily large MR ratios, others had different tunnel resistances according to different current-flow paths, and-Some had characteristics of both, In contrast, junctions with well oxidized Al barriers exhibited a large tunnel resistance and good stability. The Ni-Fe/Co/Al-AlOx/Co/Ni-Fe/Fe-Mn/Ni-Fe junction showed spin-valve-like R-H properties. The MR ratio was 10% for a 20 Oe magnetic field.