Local control of magnetic damping in ferromagnetic/non-magnetic bilayers by interfacial intermixing induced by focused ion-beam irradiation

Abstract

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Evolution of damping in ferromagnetic/nonmagnetic thin film bilayers as a function of nonmagnetic layer thickness

“…2(a) and 2(c) with three characteristic regions can be understood by considering several intrinsic and extrinsic effects occurring at the interface of the FM and NM layers. It is known that d-d hybridization, spin-pumping, and two-magnon scattering are the effective factors for damping enhancement in FM/NM thin films [3,4,11,13,17,21,23]. The experimental results are in agreement with a recent theoretical study [3] where damping increases with increasing Pt capping layer thickness up to a broad peak followed by a decrease to constant value with further increases in thickness.…”

“…This can occur when the symmetry of the system is disturbed by structural defects like film roughness and intermixing [1,3,21] and will enhance the effective damping of the magnetization precession. Increased intermixing will also enhance the effective spin-mixing conductance [8,21,22], and modifying the interface will affect all of the mechanisms mentioned above [4,23]. It is therefore of great interest to study the evolution of precessional magnetic damping in FM/NM bilayers as the interface develops as a function of the NM thickness.…”

Time-domain detection of current controlled magnetization damping in Pt/Ni81Fe19 bilayer and determination of Pt spin Hall angle

“…is observed that a remains almost constant over a range of frequency between 8.5 to 15 GHz, from which it is inferred that in this sample, extrinsic phenomena, 24 such as two magnon scattering, do not contribute to the effective damping. In order to investigate the effect of spin torque on damping, a dc current was passed through the stack.…”

Control of domain wall pinning by localised focused Ga + ion irradiation on Au capped NiFe nanowires

“…37 It has been observed previously that interfacial intermixing at the NiFe/ Au interface increases with increasing ion dose and here this may contribute to the increased DW pinning, although the topological roughness is not significantly enhanced. Also, the magnetic damping has also been shown to increase with ion-beam irradiation 43 and this may have an effect on the dynamic interaction of a propagating DW with the pinning region in our experimental measurements. This dynamic behavior was not included in the quasi-static micromagnetic analysis performed here with an artificially high damping parameter of a ¼ 0.5.…”