Structure, materials and shape optimization of magnetic tunnel junction devices : Spin-transfer switching current reduction for future magnetoresistive random access memory application

We present a systematic study of spin transfer switching in magnetic tunneling junctions (MTJs). Several ways to decrease the switching current density through material and stack engineering and MTJ element shape optimization are explained in detail. The data are presented for switching on MgO-based MTJ with high tunnel magnetoresistance (TMR) of 150% and low intrinsic switching current density Jc0 of (2–3)×106 A/cm2. Micromagnetic modeling is used to study the spin transfer switching mechanism in nanosecond regime for spin transfer torque random access memory (STT-RAM) pillar. The importance of current-induced Oersted field on the initial onset of precession is discussed.