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

Abstract

We fabricated magnetic tunnel junctions (MTJs) of Ni 80 Fe 20/Fe 50Mn 50/Ni 80Fe 20/Al 2O 3/Co exchange-biased structures and Ni 80Fe 20/Al 2O 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 injunction 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 2O 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.