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

Abstract

We study inserting Co layer thickness-dependent spin transport and spin-orbit torques (SOTs) in the Pt/Co/Py trilayers by spin-torque ferromagnetic resonance. The interfacial perpendicular magnetic anisotropy energy density ($K_s=2.7erg/c{m}^2$), which is dominated by interfacial spin-orbit coupling (ISOC) in the Pt/Co interface, total effective spin-mixing conductance ($G_{eff,tot}=0.42\times 10^{15}{\Omega }^{-1}{m}^{-2}$) and two-magnon scattering (${\beta }_{TMS}=0.46n{m}^2$) are first characterized, and the damping-like torque (${\xi }_{DL}$ = 0.103) and field-like torque (${\xi }_{FL}$ = -0.017) efficiencies are also calculated quantitatively by varying the thickness of the inserting Co layer. The significant enhancement of ${\xi }_{DL}$ and ${\xi }_{FL}$ in Pt/Co/Py than Pt/Py bilayer system originates from the interfacial Rashba-Edelstein effect due to the strong ISOC between Co-3d and Pt-5d orbitals at the Pt/Co interface. Additionally, we find a considerable out-of-plane spin polarization SOT, which is ascribed to the spin anomalous Hall effect and possible spin precession effect due to IPMA-induced perpendicular magnetization at the Pt/Co interface. Our results demonstrate that the ISOC of the Pt/Co interface plays a vital role in spin transport and SOTs-generation. Our finds offer an alternative approach to improve the conventional SOTs efficiencies and generate unconventional SOTs with out-of-plane spin polarization to develop low power Pt-based spintronic via tailoring the Pt/FM interface.

17 pages, 4 figures

References in corpus (4)

• Determination of intrinsic spin Hall angle in Pt
• Control of current-induced spin-orbit effects in a ferromagnetic heterostructure by electric field
• Orbit-transfer torque driven field-free switching of perpendicular magnetization
• Dynamical mode coupling and coherence in spin Hall nano-oscillator with perpendicular magnetic anisotropy