Effects of temperature, deposition conditions, and magnetic field on Ni/sub 80/Fe/sub 20//Fe/sub 50/Mn/sub 50//Ni/sub 80/Fe/sub 20//Al/sub 2/O/sub 3//Co and Ni/sub 80/Fe/sub 20//Al/sub 2/O/sub 3//Co magnetic tunnel junctions

Abstract

We fabricated magnetic tunnel junctions (MTJs) of Ni 80 Fe 20 Fe 50 Mn 50 Ni 80 Fe 20 Al 2 O 3 Co exchange-biased structures and Ni 80 Fe 20 Al 2 O 3 Co nonexchange-biased structures using shadow masks, with and without an in situ magnetic field. We magnetically annealed the junctions at 230 C for 15 min after deposition. Low-temperature measurements revealed an increase in junction resistance and tunneling magnetoresistance and enhancement of the exchange field for exchange-biased junctions. Post-deposition magnetic annealing at an optimum predicted temperature did not improve the quality of the Al 2 O 3 but instead degraded it, highlighting the importance of other contributing factors. MTJs fabricated with an in situ magnetic field without any post-deposition magnetic annealing produced the most desirable results from the perspective of magnetic application technology.Index Terms-Exchange bias, magnetic field sputtering, magnetic tunnel junctions, post-deposition magnetic annealing.

Localized annealing of polysilicon microstructures by inductively heated ferromagnetic films

“…A standard procedure in the processing of ferromagnetic films, magnetic annealing is a means by which magnetic properties can be optimized for the desired application. The literature provides numerous examples of magnetic annealing for the conditioning of domains in both the in-plane [Mizutani, et al, 2000;Garcia, et al, 2002;Vas'ko, et al, 2002;Chen, et al, 2005] and normal [Garcia, et al, 2002;Zhang, et al, 2004] orientations. In Mizutani, et al, 2000, 0.8µm Co 56 Ni 14 Fe 30 alloys were electroplated under an 80Oe magnetic field applied parallel to the substrate, establishing an in-plane easy axis, and annealed in a vacuum ambient at temperatures ranging from 150-400 o C with a 100Oe in-plane field applied either parallel or perpendicular to the easy axis.…”