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

We fabricated magnetic tunnel junctions (MTJs) of 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 exchange-biased structures and Ni/sub 80/Fe/sub 20//Al/sub 2/O/sub 3//Co nonexchange-biased structures using shadow masks, with and without an in situ magnetic field. We magnetically annealed the junctions at 230/spl deg/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/sub 2/O/sub 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.