The dependency of tunnel magnetoresistance ratio on nanoscale thicknesses of Co sub(2)Fe sub(6)B sub(2) free and pinned layers for Co sub(2)Fe sub(6)B sub(2) /MgO-based perpendicular-magnetic-tunnel-junctions

The tunnel magnetoresistance (TMR) ratio of a cobalt-iron-boron (CoFeB)-based perpendicular-magnetic-tunnel-junction (p-MTJ) spin valve is extremely sensitive to both nanoscale Co sub(2)Fe sub(6)B sub(2) free- and pinned-layer thicknesses. The TMR ratio peaks at a Co sub(2)Fe sub(6)B sub(2) free-layer thickness of 1.05 nm, while it peaks at a Co sub(2)Fe sub(6)B sub(2) pinned-layer thickness of 1.59 nm, achieving 104%. The amount of tantalum diffused into the MgO tunneling barrier (originated from a tantalum seed) decreases with increasing Co sub(2)Fe sub(6)B sub(2) free-layer thickness, while the amount of palladium diffused from a [Co/Pd] sub(n) SyAF layer decreases with increasing Co sub(2)Fe sub(6)B sub(2) pinned-layer thickness, determining the crystallinity of the MgO tunneling barrier and the TMR ratio. In addition, the TMR ratio tended to decrease when the Co sub(2)Fe sub(6)B sub(2) free layer and the Co sub(2)Fe sub(6)B sub(2) pinned layer switched characteristics from interface-perpendicular anisotropic to in-plane anisotropic.