Thickness and Oxidation Time Dependence of Tunnel Magnetoresistance in Ni-Fe/Co/Al-O/Co Junctions

Abstract

Ni-Fe/Co/Al-O/Co tunnel junctions with small active areas down to 3 x 3 μm² were fabricated by the micro-fabrication technique. The Al-O insulating layer was prepared by plasma oxidation of a thin sputtered Al film. The dependences of the tunnel magnetoresistance on the thickness of the Al film and the oxidation time were investigated. The interface structure of the junction was observed by using high-resolution electron microscopy. The relationship between the magnetoresistive properties and the interface structure is discussed.