2 research outputs found
Tailoring the switching efficiency of magnetic tunnel junctions by the fieldlike spin-orbit torque
Current-induced spin-orbit torques provide a versatile tool for switching
magnetic devices. In perpendicular magnets, the dampinglike component of the
torque is the main driver of magnetization reversal. The degree to which the
fieldlike torque assists the switching is a matter of debate. Here we study the
switching of magnetic tunnel junctions with a CoFeB free layer and either W or
Ta underlayers, which have a ratio of fieldlike to dampinglike torque of 0.3
and 1, respectively. We show that the fieldlike torque can either assist or
hinder the switching of CoFeB when the static in-plane magnetic field required
to define the polarity of spin-orbit torque switching has a component
transverse to the current. In particular, the non-collinear alignment of the
field and current can be exploited to increase the switching efficiency and
reliability compared to the standard collinear alignment. By probing individual
switching events in real-time, we also show that the combination of transverse
magnetic field and fieldlike torque can accelerate or decelerate the reversal
onset. We validate our observations using micromagnetic simulations and
extrapolate the results to materials with different torque ratios. Finally, we
propose device geometries that leverage the fieldlike torque for density
increase in memory applications and synaptic weight generation
Field-free spin–orbit torque driven switching of perpendicular magnetic tunnel junction through bending current
International audienceCurrent-induced spin–orbit torques (SOTs) enable fast and efficient manipulation of the magnetic state of magnetic tunnel junctions (MTJs), making them attractive for memory, in-memory computing, and logic applications. However, the requirement of the external magnetic field to achieve deterministic switching in perpendicularly magnetized SOT-MTJs limits its implementation for practical applications. Here, we introduce a field-free switching (FFS) solution for the SOT-MTJ device by shaping the SOT channel to create a “bend” in the SOT current. The resulting bend in the charge current creates a spatially nonuniform spin current, which translates into inhomogeneous SOT on an adjacent magnetic free layer enabling deterministic switching. We demonstrate FFS experimentally on scaled SOT-MTJs at nanosecond time scales. This proposed scheme is scalable, material-agnostic, and readily compatible with wafer-scale manufacturing, thus creating a pathway for developing purely current-driven SOT systems