Spin pumping in ion-beam sputtered Co2FeAl/Mo bilayers: Interfacial Gilbert damping

Abstract

The spin pumping mechanism and associated interfacial Gilbert damping are demonstrated in ion-beam sputtered Co2FeAl (CFA)/Mo bilayer thin films employing ferromagnetic resonance spectroscopy. The dependence of the net spin current transportation on Mo layer thickness, 0 to 10 nm, and the enhancement of the net effective Gilbert damping are reported. The experimental data has been analyzed using spin pumping theory in terms of spin current pumped through the ferromagnet/nonmagnetic metal interface to deduce the effective spin mixing conductance and the spin-diffusion length, which are estimated to be 1.16(±0.19)×10 19 m −2 and 3.50±0.35nm, respectively. The damping constant is found to be 8.4(±0.3)×10 -3 in the Mo(3.5nm) capped CFA(8nm) sample corresponding to a ~42% enhancement of the original Gilbert damping (6.0(±0.3)×10 -3 ) in the uncapped CFA layer. This is further confirmed by inserting a Cu dusting layer which reduces the spin transport across the CFA/Mo interface. The Mo layer thickness dependent net spin current density is found to lie in the range of 1-3 MAm -2 , which also provides additional quantitative evidence of spin pumping in this bilayer thin film system.

High temperature stability in few atomic layer MoS2 based thin film heterostructures: structural, static and dynamic magnetization properties

“…1(b)) indicates them to be 2-, 3-, and 4L-thick MoS 2 layers which is consistent with the reported values in the literature. 43 The behaviour of E 2g and A 1g as a function of the number of layers has several intriguing characteristics. Most strikingly, the E 2g vibration softens (red shifts), while the A 1g vibration stiffens (blue shifts) with increasing sample thickness.…”

Observation of Skyrmions at Room Temperature in Co2FeAl Heusler Alloy Ultrathin Film Heterostructures

“…The i -DMI energy density can be determined either by modeling the full spin-wave frequency vs. wave-vector dispersion with a modified dispersion relation for DE spin waves by introducing the DMI term or from the frequency difference ( Δf ) between spin-waves with opposite (+ k and − k ) wave-vectors, which is given by 37 ,Where, is the frequency difference, k x is the x -component of the wave vector, is the gyromagnetic ratio, D is the i -DMI energy density and M s is the saturation magnetization. In our case, we have chosen the latter method for determining D , as the estimation of D here is primarily determined by the experimentally measured quantities Δ f , k x and M s (=1000 ± 50 kA/m is used for thick films 44 ). Figure 5(a,d) show typical BLS spectra, recorded from Ta/CFA( t )/MgO thin film heterostructures with t = 10 and 5 nm, respectively.…”

“…To the best of our knowledge, the existence of skyrmions in high spin-polarized materials, i . e ., full Heusler alloys such as Co 2 FeAl (CFA) which possess low damping constant 34 , high Curie temperature 20 , large spin polarization 43 and tunable spin-dynamics properties 44,45 is yet to be reported. Despite the rapidly increasing number of experimental studies for gaining further insight into understanding the stabilization of skyrmions in ultrathin films, the robust formation of skyrmions at room temperature in large continuous thin films continues to be an exciting area.…”

Interfacial magnetic anisotropy controlled spin pumping in Co60Fe20B20/Pt stack

“…The control over the generation and detection of the pure spin current is achieved by material engineering of HMs with enhanced SOC interfacing with FM 17 . The most studied HMs with large SOC explored via spin pumping are the 4d and 5d metals, such as Pt 18,19 , Pd 20,21 , Mo 22 , β-W 23 , β-Ta 24 . The direction-sensitive flow of pure spin current can possibly be realized by controlling (i) the magnetic anisotropy of the spin sink layer and relative alignment of the two magnetic layers in the FM/spacer/FM structure 25 and (ii) the crystalline symmetry of the ferromagnet where anisotropic Gilbert damping can be tuned by magnetization orientation 26,27 .…”