Hf thickness dependence of spin-orbit torques in Hf/CoFeB/MgO heterostructures

Abstract

We have studied the spin-orbit torques in perpendicularly magnetized Hf/CoFeB/MgO system, by systematically varying the thickness of Hf underlayer. We have observed a sign change of effective fields between Hf thicknesses of 1.75 and 2 nm, indicating that competing mechanisms, such as the Rashba and spin Hall effects, contribute to spin-orbit torques in our system. For larger Hf thicknesses (>2 nm), both the components of spin-orbit torques arise predominantly from the bulk spin Hall effect. We have also confirmed these results using spin-orbit torque induced magnetization switching measurements. Our results could be helpful in designing Hf based SOT devices.

Modulated switching current density and spin-orbit torques in MnGa/Ta films with inserting ferromagnetic layers

“…The value of ζ  ≡ ( ρ N t F /ρ F d ) describes the current shunting effect into the magnetic layer. We have extracted the effective spin Hall angle θ SH   = −0.11 of Ta in MnGa/Ta using the relationship H L   =  ħ θ SH |j|/(2| e |M S t F ), where j is charge current density, e the charge of an electron, M S the saturation magnetization of MnGa, and t F the thickness of MnGa35. In MnGa/Co/Ta, P   = 0.3, ρ N   = 125  μ Ω cm , θ SH   = −0.11, λ N   = 1.26  nm, ρ F   = 385  μ Ω cm , and t F   = 3.8  nm are fixed, and Re [G MIX ]   = 10 15  Ω −1 cm −2 are assumed.…”

Current-induced magnetization switching in Pt/Co/Ta with interfacial decoration by insertion of Cr to enhance perpendicular magnetic anisotropy and spin–orbit torques

“…In such a SOT-based device, when an in-plane charge current (J e ) flows through HM with strong spin-orbit coupling (SOC) including 5d-metal Pt [2], Ta [11], W [12], and Hf [13], etc., it can be converted into a pure spin current (J s ). Then, J s injects into FM and generates a torque to act on magnetic moments.…”

Anomalous Hall effect and spin-orbit torques in MnGa/IrMn films: Modification from strong spin Hall effect of the antiferromagnet

“…The AFM IrMn has not only generated SOT but also supplied an in-plane exchange bias field, which enables all-electrical deterministic switching of perpendicular magnetization in the , where J C is charge current density, e is the charge of an electron, is the saturation magnetization of MnGa, and is the thickness of the MnGa [42]. The value of IrMn is larger than the result in the previous studies [41], which may be ascribed to the different experimental method.…”