Controllable Spin–Orbit Torque Efficiency in Pt/Co/Ru/Co/Pt Multilayers with Interlayer Exchange Couplings

Abstract

The magnetization manipulation by the current-induced spin–orbit torque opens a prospect for energy-efficient spintronic applications. Here, we investigate controllable spin–orbit torques (SOTs) realized by interlayer exchange coupling (IEC) in Pt/Co/Ru/Co/Pt stacks. The interlayer magnetization realignments originate from the competition between itinerant electron diffusion and current-induced spin current relaxation, and it is revealed that the long-ranged interlayer antiparallel orders exist with a Ru spacer thickness of 2.3 nm. The current-induced hysteresis-loop-shift method is used to assess the H z eff/J depending on the different spacer thicknesses. The loop shift distributions are revealed with the H z eff phase diagrams to characterize the difference between FM-IEC and AFM-IEC. Combining with micromagnetic simulations, a possible transition mechanism of H z eff/J is discussed by combining magnetization switching with the in-plane bias field in IEC systems. This work demonstrates that the spin current realigned IEC mechanism can efficiently control the SOTs in both ferromagnetic and antiferromagnetic multilayers.

Study of Spin–Orbit Interactions and Interlayer Ferromagnetic Coupling in Co/Pt/Co Trilayers in a Wide Range of Heavy-Metal Thickness

“…Also, the recent studies on Pt/Co/Ru/Co/Pt showed that the RKKY interlayer exchange coupling (IEC) could tailor the properties of the multilayers. 49 …”

“…Also, the recent studies on Pt/Co/Ru/Co/Pt showed that the RKKY interlayer exchange coupling (IEC) could tailor the properties of the multilayers. 49 In this paper, we present the detailed studies of the Co/Pt/ Co system with the use of the electrically detected FMR (ferromagnetic resonance), as well as low-frequency harmonic Hall voltage and static magnetotransport measurements. Here, the Pt layer plays a double role in the considered structure, first as a source of substantial spin currents and second as an essential element of the exchange ferromagnetic coupling mechanism.…”

“…Among them, we find CoFeB-based structures like W/i-CoFeB/Pt and p-CoFeB/Ta, as well as the Co-based multilayers like p-Co/Pt/i-Co, p-Co/Pt, − i-Co/Ta, Ta/i-Co/Pt, Ru/p-Co/Ru, and Ru/p-Co/Ru/W, where p­(i) stands for perpendicular­(in-plane) anisotropy. Also, the recent studies on Pt/Co/Ru/Co/Pt showed that the RKKY interlayer exchange coupling (IEC) could tailor the properties of the multilayers …”

Disentangling complex current pathways in a metallic Ru/Co bilayer nanostructure using THz spectroscopy

“…Here, we applied THz-TDS to studies of conduction in technologically-relevant metallic bilayer Ru/Co nanostructures of different thicknesses [14][15][16] , and of their individual constituent metals Ru and Co. Such structures find applications, among others, in spin-torque devices 17,18 , as well as in structures featuring magnetic skyrmions. [19][20][21] All the THz conductivity spectra measured in our work could be well described by the Drude model of free carrier conduction, and the conductivity of bilayers was analyzed based on an effective resistor network model.…”