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(a) An SEM image of a patterned rectangular pillar. (b) AFM image of several pillars. (c) AFM topographic profile across two pillars indicated by the white line in (b). From the height shown in the AFM profile, we conclude that the pillars were patterned through the whole magnetic stack and into the bottom Ta electrode.
vs for 82 pillars using the same probe. The sizes ranged from down to . The best linear fit was given by the line with and average combined probe and contact resistance of . Each size showed moderate resistance variations caused by a combination of contact resistance variation and slight variations in the patterned feature sizes.
Resistance vs in-plane magnetic field for a rectangular pillar, having an and a coupling offset of . The coupling offset was due to the field produced by the pinned SAF beneath the tunnel barrier. A dc current bias of with 16.7 ms integrations was used. The sweep started at positive field sweeping down (1, 2) and ended sweeping up (3, 4).
Resistance as a function of current on the same MTJ pillar as in Fig. 3, starting at 1.5 mA sweeping down to −1.5 mA (1, 2, and 3) and then back up to 1.5 mA (4, 5, and 6). The integration time for each voltage measurement was 1.5 ms. A bias field of −12 G was applied to the long axis of the pillar to ensure bistability. The parallel to antiparallel switch occurred at and the antiparallel to parallel switch occurred at . The sloped sections of the curve where resistance decreased with increasing current magnitude (both polarities) were due to the decrease of magnetoresistance with increasing bias voltage.
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