Dipole-coupled core-shell perpendicular-shape-anisotropy magnetic tunnel junction with enhanced write speed and reduced crosstalk

The concept of perpendicular-shape-anisotropy spin-transfer-torque magnetic random-access memory tackles the downsize scalability limit of conventional ultrathin magnetic tunnel junctions below sub-20-nm technological nodes. This concept uses a thicker storage layer with a vertical aspect ratio, enhancing the thermal stability factor Δ thanks to the favorable contribution of the shape anisotropy. However, the increased aspect ratio comes with an increase in switching time under applied voltage and the crossover to nonuniform reversal mechanism at higher aspect ratio, limiting the gain in scalability. Additionally, the larger volume of the magnetic cell significantly increases the stray field acting on the neighboring devices compared to thin magnetic tunnel junctions. In this work, we propose the use of a dipole-coupled core-shell system as a storage layer. This improves both bottlenecks, as predicted by micromagnetic simulations for magnetization reversal, and a macrospin model to estimate the stray field in a dense array.