Magnetization dynamics in the presence of pure spin currents in magnetic single and double layers in spin ballistic and diffusive regimes

Abstract

In this paper we study the spin transport by using the spin-pumping effect in epitaxial magnetic single and double layer film structures. For the magnetic single layer sample we show the spin-pumping-induced interface damping increases and saturates with the Au capping layer thickness. In addition magnetic double layer structures allowed us to investigate both the spin-pump and spin-sink effects. Coupling of pure spin currents to the magnetization via spin-sink effect is studied using time-resolved magneto-optical Kerr effect. These measurements were used to study the propagation of pure spin currents across a Au spacer layer between the two ferromagnets. The propagation of spin momentum density through the Au spacer layer was well described by spin-diffusion equation, which takes into account electron momentum and spin-flip scattering. The spindiffusion theory was integrated into modified Landau-Lifshitz equations accounting in self-consistent manner for spin-pump/sink mechanism and spin momentum density propagation. Good agreement between theory and experimental data was found.

Enhanced spin pumping near a magnetic ordering transition

“…In magnetic multilayers and heterostructures, spin pumping is often found to be one of the dominant contributions to magnetic relaxation 13,14 . Because spin pumping enables the generation of pure spin currents in normal metals adjacent to ferromagnets 15,16 , which in turn can be detected using the inverse spin…”

Dependence of spin pumping and spin transfer torque upon Ni81Fe19 thickness in Ta/Ag/Ni81Durrant1, Shelford2, Valkass3 et al. 2017Phys. Rev. B13170View full textAdd to dashboardCite

“…The dynamics of the sink layer have previously been observed by time-resolved magneto-optical Kerr effect studies 22,26,27 of epitaxial structures with Ag and Au spacer layers. In spin valves with chemically distinct source and sink layers the element selectivity of x-ray magnetic circular dichroism (XMCD) 28 can be employed to isolate the dynamic response of the source and sink layers and directly probe the spin torque acting on the sink layer.…”

Detection and quantification of inverse spin Hall effect from spin pumping in permalloy/normal metal bilayers

“…Spin pumping in Py/N bilayers Spin pumping generates pure spin currents in N, when they are in contact with a ferromagnet with time-dependent magnetization induced, e.g., by ferromagnetic resonance ͑FMR͒. [17][18][19][20][21] The instantaneous spin-pumping current j s 0 at the Py/N interface is given by 22,23 …”