Spin orbit torques in Pt-based heterostructures with van der Waals interface*

Abstract

Spin orbit torques (SOTs) in ferromagnet/heavy-metal heterostructures have provided great opportunities for efficient manipulation of spintronic devices. However, deterministically field-free switching of perpendicular magnetization with SOTs is forbidden because of the global two-fold rotational symmetry in conventional heavy-metal such as Pt. Here, we engineer the interface of Pt/Ni heterostructures by inserting a monolayer MoTe2 with low crystal symmetry. It is demonstrated that the spin orbit efficiency, as well as the out-of-plane magnetic anisotropy and the Gilbert damping of Ni are enhanced, due to the effect of orbital hybridization and the increased spin scatting at the interface induced by MoTe2. Particularly, an out-of-plane damping-like torque is observed when the current is applied perpendicular to the mirror plane of the MoTe2 crystal, which is attributed to the interfacial inversion symmetry breaking of the system. Our work provides an effective route for engineering the SOT in Pt-based heterostructures, and offers potential opportunities for van der Waals interfaces in spintronic devices.

Enhancement of spin-orbit torque efficiency by tailoring interfacial spin-orbit coupling in Pt-based magnetic multilayers

“…The AMR exhibits the sinusoidal dependence on magnetization with a period of 180 • , R AMR ∝ sin 2ϕ. Considering the generated spin currents with all possible spin polarizations, we can derive the general formula for describing IP angular-dependent V a and V s of ST-FMR voltage as follows: [41,42] V a = (V a,y cosϕ +V a,z +V a,x sinϕ) sin2ϕ,…”

“…Where 𝑅 FM and 𝑅 HM are the resistance of the total FM and Pt layers, respectively, and 𝐴 𝑐 is the cross-sectional area of the Pt layer. currents with all possible spin polarizations, we can derive the general formula for describing IP angular-dependent 𝑉 a and 𝑉 s of ST-FMR voltage as follows [41,42]:…”

Orbital torque of Cr-induced magnetization switching in perpendicularly magnetized Pt/Co/Pt/Cr heterostructures

“…Spin orbital torques (SOTs) in heavy metal/ferromagnetic bilayers attracted much attention due to its capability to efficiently drive the magnetization switching for magnetic memories and spin logic devices via the spin Hall effect of heavy metals and/or the interfacial Rashba effect. [1][2][3][4][5] So far, the promising materials for SOT-driven magnetization switching rely on heavy metals (HMs), [3,4] and 2d materials [6,7] and topological insulators [8][9][10] due to their strong spin current generating ability. The orbital torque from orbital current as the counterpart of spin orbital torque from spin current in materials was reported by Bernevig et al in p-doped silicon, [11] 4d/5d transition metals, [12,13] and in 3d-transition light metals (LM) or CuO x .…”