Study on Ni80Fe20/Al2O3/Co magnetic tunnel junctions

With plasma oxidization to create an insulating layer of Al2O3, we have rep eatedly fabricated some Ni80Fe20/Al2O3/Co magnetic tunnel junctions (MTJ), which show obvious tunneling magnetoresistance (TMR) effect. The insulating layer is well formed by the oxidization procedure, which is verified by op tical spectra and other measurement results. At room temperature, the maxim um TMR ratio reaches 6.0%. The switch field can be less than 800 A/m and th e relative step width is about 2400 A/m. The junction resistance R-j change s from hundreds of ohms to hundreds of kilohms and TMR ratio decreases mono tonously with the increase of applied junction voltage bias (under zero mag netic field).