Effect of recording layer thickness on reducing switching current in double MgO/CoFeB interfaces pMTJ

Abstract

The effect of the recording layer thickness (t) on the quasi-static switching characteristics in the double MgO/CoFeB interfaces perpendicular magnetic tunnel junctions with the [Co/Pt]n-based synthetic antiferromagnetic structures has been investigated. It is apparent that the switching current drops rapidly either with slightly increasing the bottom CoFeB thickness (tCoFeB ≥ 1.15 nm) or inserted Ta thickness (tTa ≥ 0.3 nm), or with marginally decreasing the upper CoFeB thickness (tCoFeB ≤ 0.75 nm), even acquiring a maximum reduction of 41.8%. The tuning mechanism of the write energy dissipation at a specific pulse width can be attributed to two parts. One is an intrinsic leverage of the effective ferromagnetic volume, spontaneous magnetization, and magnetic anisotropy field in the recording layers with a view to their dead layer. The secondary contributors may be closely related to the discrepancy between the resistance-area products of the perpendicular magnetic tunnel junction devices with the six different stack designs. Our results are instructive to the future development of practical ultralow-power chips in binary memory and logical computation fields.