Contribution of defects to the spin relaxation in copper nanowires

Abstract

The contributions to the spin relaxation in copper (Cu) nanowires are quantified by carefully analyzing measurements of both charge and spin transport in lateral spin valves as a function of temperature and thickness. The temperature dependence of the spin-flip scattering solely arises from the scattering with phonons, as in bulk Cu, whereas we identify grain boundaries as the main temperature-independent contribution of the defects in the nanowires. A puzzling maximum in the spin diffusion length of Cu at low temperatures is found, which can be explained by the presence of magnetic impurities. The results presented here suggest routes for improving spin transport in metallic nanostructures, otherwise limited by confinement effects.Comment: 10 pages, 4 figures, 1 tabl

Modulation of pure spin currents with a ferromagnetic insulator

“…2(c), where R NL changes from positive to negative when the relative magnetization of the FM electrodes changes from parallel (P) to antiparallel (AP) by sweeping H . This measurement is an unambiguous demonstration that a pure spin current is transported along the Cu channel [20][21][22][23][24][25][26][27][28][29]. It is worth noting that the relative magnetization of the Co electrodes changes at H 400 Oe, far above the saturation field of YIG (∼100 Oe).…”

“…To that end, we use lateral spin valves (LSVs). These devices allow an electrical injection and detection of pure spin currents in a NM channel by using * f.casanova@nanogune.eu ferromagnetic (FM) electrodes in a nonlocal configuration [20][21][22][23][24][25][26][27][28][29]. The LSVs have been fabricated on top of a FMI, in order to enable the magnetic gating of the pure spin currents.…”

“…This is in agreement with our experimental results discussed above. However, there is an experimental limit, since the nonlocal signal decays exponentially and will be negligible when L λ [23,26]. By decreasing the thickness (t) of the Cu channel, β increases asymptotically when t approaches 0 [ Fig.…”

“…For instance, when t ∼ 20 nm, β already increases to ∼50%. However, the decrease of λ with t [26], which has not been taken into account for the representation, will lower β. The most effective way of improving β seems to be increasing G r [ Fig.…”

Kondo physics in non-local metallic spin transport devices

“…Remarkably, despite the maturity of metallic spintronics, there remain large gaps in our fundamental understanding of spin transport in metals, particularly with injection of spins across ferromagnet (FM)/nonmagnetic metal (NM) interfaces, and their subsequent diffusion and relaxation. Unresolved issues include the applicability of the widely employed Elliott-Yafet (E-Y) 3 spin relaxation mechanism [4][5][6][7][8][9][10] , the influence of defects, surfaces and interfaces on spin relaxation at nanoscopic dimensions 8,[11][12][13][14][15] , the importance of magnetic and spin-orbit scattering [16][17][18] and the accuracy of existing models [19][20][21][22][23] .…”