Giant Spin Hall Effect Induced by Skew Scattering from Bismuth Impurities inside Thin Film CuBi Alloys

Abstract

We demonstrate that a giant spin Hall effect (SHE) can be induced by introducing a small amount of Bi impurities in Cu. Our analysis, based on a new three-dimensional finite element treatment of spin transport, shows that the sign of the SHE induced by the Bi impurities is negative and its spin Hall (SH) angle amounts to -0.24. Such a negative large SH angle in CuBi alloys can be explained by applying the resonant scattering model proposed by Fert and Levy [Phys. Rev. Lett. 106, 157208 (2011)] to 6p impurities.

Temperature dependence of the spin Hall angle and switching current in the nc-W(O)/CoFeB/MgO system with perpendicular magnetic anisotropy

“…Being a spin-orbit interaction derived effect, it is expected to be largest in heavy metals or lighter metals with heavy metal impurities. 8,9 The highest values for a metal were observed for β-W with the A15 structure; At the same time, high oxygen content above 25% was shown to induce a nanocrystalline growth of the W film. 12 However, the β-W phase is sensitive to high temperatures and may thus be unsuitable for integration into device fabrication processes that require sustained annealing at high temperature, e. g., during CMOS manufacturing.…”

“…Being a spin-orbit interaction derived effect, it is expected to be largest in heavy metals or lighter metals with heavy metal impurities. 8,9 The highest values for a metal were observed for β-W with the A15 structure; …”

Spin Orbit Coupling Controlled Spin Pumping and Spin Hall Magnetoresistance Effects

“…It is therefore indicated that the SHC and spin Hall angle in the NM layer can be tuned significantly via the SOC strength. As one of major issues in this field [17][18][19][20][21][22] , the mechanism of the extrinsic SHC needs further investigations.…”

“…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.…”

“…The issue of the SHE scaling law has not been understood yet although many attempts have been made. For instance, the intrinsic term has a dominant contribution to the spin Hall conductivity (SHC) in Ir doped Pt 18 whereas the extrinsic skew scattering plays a major role in Ir doped Cu [20][21][22] . In order to enhance the charge-spin conversion efficiency and to reveal the mechanism of the SHE, it is imperative to study the SHE in non-magnetic alloys in which the SOC strength can be tuned continuously in a wide range.…”