Temporal evolution of spin accumulation in nonlocal spin valves

Absence of high surface spin-flip rate in mesoscopic silver channels

“…Over a period of months, the magnetic impurities are gradually segregated toward the Cu surfaces and are oxidized, leading to a reduction of spin-rate and an increase of spin signals. 11,16) This is consistent with a related study, where NLSV structures with Cu channels fabricated by shadow evaporation with thin magnetic injector/detectors show longer s than structures with thicker injector/detectors. 17) Regarding devices with Ag channels, the Ni and Fe impurities are more likely to be located in the bulk due to the motion of Ag islands on the substrate during the expansion.…”

“…11,13,14) Our previous work indicates that the origin of the high surface spin-flip rate is the magnetic impurities located near the side surfaces of the nonmagnetic channel. 11,16,17) Another study 18) suggests a different origin of Kondo effects, which are also interestingly attributed to magnetic impurities in the nonmagnetic channel.…”

“…Our previous work indicates that the magnetic impurities embedded near the side surfaces of the nonmagnetic channel are culprits for high surface spin-flip rate. 11,16,17) During the deposition of Py from an oblique angle, as shown in Fig. 1(b), a substantial amount of Ni and Fe is accumulated on the side walls of the PMMA resist, as shown in Fig.…”

Temperature evolution of spin-transfer switching in nonlocal spin valves with dipolar coupling

“…The thin AlO x layer is placed between the Py and Cu to enhance the spin injection and detection polarizations [18]. The center-to-center separation (L) between F 1 and F 2 is 200 nm, which is shorter than the spin diffusion length l s $ 600 nm [19,20] of Cu at 4.2 K.…”