Seed influence on the ferromagnetic resonance response of Co/Ni multilayers

Abstract

The effect of Pd and Ru seed layers on the magnetic properties of [Co/Ni]N multilayers with varying number of bilayer repeats N is investigated using vector network analyzer ferromagnetic resonance. The effective anisotropy field HKeff is found to increase with N for Ru seed, but decreases for Pd until N = 15. As N is increased beyond 15, HKeff decreases for both seeds. In contrast, the damping parameter α decreases with N regardless of the seed, showing a 1/N dependence. Taking spin pumping into account, the intrinsic damping α0 for both Pd and Ru seeds reduce to α0 ≈ 0.01. These results demonstrate that there can be a strong influence of the seed/Co interface on anisotropy, especially for sufficiently low N, but not necessarily on α0.

Effect of deposition technique of Ni on the perpendicular magnetic anisotropy in Co/Ni multilayers

“…Generally a decrease in H K eff is observed after this n value. In Co/Ni multilayered films, such kind of a trend, (for smaller n values increasing H K eff and for greater n values decreasing H K eff ), was reported for several times [11,12,14]. There are two common explanations for decreasing H K eff with increasing n in Co/Ni multilayered films.…”

“…On the other hand, due to other explanation, after a certain value of n, it is indispensable the roughness of the multilayers increases because of an increase in the number of structural defects. This increase in roughness causes a decrease in the strength of PMA [12,14]. Fig.…”

“…Previously some growth parameters such as number of repetition of Co/Ni bilayers [10][11][12], growth rates [5] and thicknesses [13] of Co and Ni layers, type of buffer layers [12] and annealing [14,15] have been reported to be effective on magnetic properties of Co/Ni multilayers. The deposition technique was also reported to be effective on magnetic properties of Co/Ni multilayered films [16,17].…”

Resolving the controversy of a possible relationship between perpendicular magnetic anisotropy and the magnetic damping parameter

“…We show conclusively that variation of the orbital-moment asymmetry, and not a change in n, is the fundamental mechanism by which the anisotropy is altered, and that the damping parameter is independent of such a mechanism. In addition, we explicitly demonstrate how improper accounting for spin-pumping, 5,12,27,28 two-magnon scattering, [29][30][31] and inhomogeneous broadening [32][33][34] can lead to a spurious dependence of damping on anisotropy.…”

Ultrafast Magnetization Dynamics in Multilayered Films Down to the Few-cycle Regime

“…These multilayers are formed by alternating ultrathin layers which generates a large number of interfaces. The alternating ultrathin layers are usually formed by two ferromagnetic materials, such as Co/Ni [45]- [47] and CoFe/Ni [48], or by the combination of nonmagnetic/ferromagnetic bilayers such as in Co/Pt [49]- [51], Co/Pd [52] or CoFe/Pt [53] multilayers.…”