Influence of interlayer roughness on magnetoresistive effect of ferromagnetic tunneling junctions

Ferromagnetic tunneling 80NiFe/Co/Al-oxide/Co junctions with wedge shaped A l-oxide were fabricated. For preparing Al-oxide, pure Al was sputtered with out exposure. The tunnel resistance for junctions with sufficiently oxidize d Al increased exponentially with increasing d(Al) On the other hand, the t unnel resistance for junctions with an air-leak scattered. The tunneling ma gnetoresistive effect (TMR) was observed at about 7 Angstrom Al for junctio ns without exposure. The surface roughness of the sample without exposure w as quite small, while that with an air-leak tended to be large with increas ing oxidization time and also d(Al). The corresponding tunnel resistance wa s very small for the junction with the rough interface. (C) 1999 Elsevier S cience B.V. All rights reserved.