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

Abstract

Spin pumping is a mechanism that generates spin currents from ferromagnetic resonance over macroscopic interfacial areas, thereby enabling sensitive detection of the inverse spin Hall effect that transforms spin into charge currents in nonmagnetic conductors. Here we study the spin-pumping-induced voltages due to the inverse spin Hall effect in permalloy/normal metal bilayers integrated into coplanar waveguides for different normal metals and as a function of angle of the applied magnetic field direction, as well as microwave frequency and power. We find good agreement between experimental data and a theoretical model that includes contributions from anisotropic magnetoresistance and inverse spin Hall effect. The analysis provides consistent results over a wide range of experimental conditions as long as the precise magnetization trajectory is taken into account. The spin Hall angles for Pt, Pd, Au, and Mo were determined with high precision to be 0.013Ϯ 0.002, 0.0064Ϯ 0.001, 0.0035Ϯ 0.0003, and −0.0005Ϯ 0.0001, respectively.

Study of spin pumping in Co thin film vis-à-vis seed and capping layers using ferromagnetic resonance spectroscopy

“…In addition, it has relatively poor spin scattering efficiency due to relatively long spin diffusion length of 10 nm [31] as compared to Pt (3.5 to 10 nm) [19,20]. This is corroborated by the increase in the value of the inhomogeneous broadening H 0 .…”

“…In addition, it affects the damping properties critically by various seed and capping layers. Recently, research has been focussed to understand the effect of heavy metal as seed and capping layers [17][18][19][20][21][22]. In a recent report Tokac et al [21] have shown that the effective spin conductance mixing strongly depends on the interfaces of seed (Ta/Cu) and capping (Cu or Ir) layers.…”

Systematic variation of spin-orbit coupling withd-orbital filling: Large inverse spin Hall effect in3dtransition metals

“…SHE depends on the SOC and θ SH is a measure of the strength of SOC. Because of the generally accepted Z 4 dependence of SOC, measurement of θ SH has been focused on heavy elements by SHE [8] or inverse spin Hall effect (ISHE) [9][10][11][12][13][14][15], while 3d metals have rarely been studied [16,17].…”

“…Ferromagnetic resonance (FMR) spin pumping of pure spin currents from a ferromagnet (FM) into a nonmagnetic (NM) material provides a powerful technique for measurement of θ SH in a broad range of materials [7,9]. We report a systematic study of the ISHE in a series of 3d transition metals using FMR spin pumping from Y 3 Fe 5 O 12 (YIG) epitaxial films into Ti, V, Cr, Mn, Fe 50 Mn 50 (FeMn), Fe 20 Ni 80 (Py), Ni, and Cu.…”

“…θ SH is a measure of SOC and can be calculated from [9,10,12,14], respectively, of the Cr layer, SD is the spin diffusion length of Cr, is the interfacial spin mixing conductance, P = 1.21 is a factor arising from the ellipticity of the magnetization precession [7], γ is the gyromagnetic ratio, h rf = 0.25 Oe is the rf field at P rf = 200 mW [7], and α is the Gilbert damping constant of YIG. To calculate θ SH , we first determine SD from the Cr thickness (t Cr ) dependence of V ISHE [ Fig.…”