The switching behaviors of submicron magnetic tunnel junctions with synthetic antiferromagnetic free layers

Abstract

The switching behaviors in elliptic shaped (aspect ratio=2) submicron magnetic tunnel junctions using CoFeB single free layer and CoFeB∕Ru∕CoFeB synthetic antiferromagnetic (SAF) free layers are studied. It is found that under considerable stray fields originating from pinned layers, junctions with single free layer show complex switching behaviors with larger Hc variations. In contrast, junctions with SAF free layers exhibit kink-free R-H loops and less Hc variations. The Hc of junctions with SAF free layers is less dependent on the junction size than that with a single free layer. Furthermore, for junctions smaller than a critical size the SAF free layers have a smaller Hc than single free layers.

SAF exhibits better resistance to roughness edge than single-free layer

“…Because of the unbalanced pinned layers, the R-H loops shift to left, and the kinks occur frequently when the magnetization reverses from low to high resistance state. The simulation results are very similar to the experimental data [7]. However, the R-H loops of SAF-free layer junctions are kink free in all defect types (shown in Fig.…”

“…In order to solve the problem, the tendency of MTJ is using synthetic antiferromagnetic (SAF) free layer to substitute single-free layer in recent years [1][2][3]. Many theoretical and experimental results have been proposed to prove the superiority of SAF-free layer [1][2][3][4][5][6][7]. The experimental results show that the R-H loops of SAF-free layer structures are almost kink free.…”

“…The experimental results show that the R-H loops of SAF-free layer structures are almost kink free. However, the kink states of the R-H loops in single-free layer structures always occur at the magnetization switching from low resistance state to high resistance state [7]. It means the magnetization reverses almost coherently in SAF-free layer structure.…”