Field-Free Type- x Spin-Orbit-Torque Switching by Easy-Axis Engineering
Journal
Physical Review Applied
Journal Volume
18
Journal Issue
3
Date Issued
2022-09-01
Author(s)
Abstract
The current-induced type-x spin-orbit-torque (SOT) switching configuration describes the orthogonal relationship between the magnetic easy axis (EA) of a ferromagnetic (FM) layer and the injected spin polarization, σ, from a heavy-metal (HM) layer, which has the potential to eclipse the conventional type-y scenario (EA parallel to σ) at the sub-nanosecond pulse regime. Here, we show that, in HM/FM bilayer heterostructures, current-driven differential planar Hall signals can serve as efficient means to probe type-x SOT switching in a simple measurement fashion. Through this approach, we demonstrate field-free type-x SOT switching in all devices with a canted EA, which are engineered via field-annealing processes. By analyzing the switching-phase diagrams, we further verify that such field-free switching stems from a z-direction effective field contributed to by both the dampinglike torque and the canted EA. Our work indicates that the canted EA, as engineered by a field-annealing process, can give rise to a robust field-free SOT switching and further reduce the critical switching current density.
Subjects
PERPENDICULAR MAGNETIZATION; DRIVEN
Publisher
AMER PHYSICAL SOC
Type
journal article