Indication of intrinsic spin Hall effect in4dand5dtransition metals

Abstract

We have investigated spin Hall effects in 4d and 5d transition metals, Nb, Ta, Mo, Pd and Pt, by incorporating the spin absorption method in the lateral spin valve structure; where large spin current preferably relaxes into the transition metals, exhibiting strong spin-orbit interactions. Thereby nonlocal spin valve measurements enable us to evaluate their spin Hall conductivities. The sign of the spin Hall conductivity changes systematically depending on the number of d electrons. This tendency is in good agreement with the recent theoretical calculation based on the intrinsic spin Hall effect.

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

“…We note that θ SH varies significantly both in sign and magnitude: θ SH is negative from Ti (n 3d+4s = 4) to FeMn (n 3d+4s = 7.5) and changes to positive for Py (n 3d+4s = 9.6), Ni (n 3d+4s = 10) and Cu (n 3d+4s = 11) while its magnitude reaches maximum at Cr (n 3d+4s = 6) and Ni (n 3d+4s = 10). The sign change in θ SH mimics the trend observed in 5d metals [7,13,27,28], while the magnitude of θ SH spans a range of almost three orders of magnitude. From Fig.…”

“…This is without considering the FM ordering in Ni. Thus, the surprisingly large values and significant variation in θ SH of 3d metals arise mainly from the delectron configuration, indicating its dominant role in spin Hall physics [7,13,27,28].…”

Spin Torque Study of the Spin Hall Conductivity and Spin Diffusion Length in Platinum Thin Films with Varying Resistivity

“…[57]. In the intrinsic SHE regime, which has recently been reported to describe Pt [39,58], and also in the side-jump regime, it is the spin Hall conductivity SH σ that is expected to be constant, independent of NM NM the NM resistivity and hence, in this study, on its thickness due to strong interfacial scattering.…”

“…Fast saturation of the damping at very thin Pt thicknesses has also been observed previously [22,37,38]. However, Liu et al [47] have recently pointed out that this very rapid attenuation is likely due to strong SML at the FM/Pt interface, and used a first principles calculation and data [61] from this measurement method to obtain 5.5 nm has been determined from a low temperature, 3-10 K, study of spin pumping in lateral spin valves [39,41] This work seems to resolve the controversy regarding the differences in the value of s λ for Pt as obtained from various spin Hall and other experiments, and demonstrates that the spin…”

Spin Orbit Coupling Controlled Spin Pumping and Spin Hall Magnetoresistance Effects

“…As an outstanding issue, however, the quantitative dependence of the SHE on the SOC strength is still unclear. Moreover, the SHE is known to be contributed by the intrinsic, the skew scattering, and the side-jump terms [17][18][19][20][21][22] . The issue of the SHE scaling law has not been understood yet although many attempts have been made.…”