Conversion of pure spin current to charge current in amorphous bismuth

Emoto, Hiroyuki; Ando, Yoshinori; Shikoh, Eiji; Fuseya, Yuki; Shinjo, Teruya; Shiraishi, Masashi

doi:10.1063/1.4863377

Cited by 21 publications

(27 citation statements)

References 25 publications

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“…The signal increases from 270 to 360 nV as the Bi thickness goes from 7.7 to 9.3 nm where it approaches its maximum and then decreases to 264 nV as the thickness is increased to 22.5 nm. This dependence with the thickness of the nonmagnetic layer is in good agreement with that recently reported by Emoto et al 13 in Py/Bi bilayers and by other authors in similar magnetic/non-magnetic bilayers.…”

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confidence: 82%

Control of the spin to charge conversion using the inverse Rashba-Edelstein effect

Sangiao

Teresa

Morellón

et al. 2015

Applied Physics Letters

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We show here that using spin orbit coupling interactions at a metallic interface it is possible to control the sign of the spin to charge conversion in a spin pumping experiment. Using the intrinsic symmetry of the "Inverse Rashba Edelstein Effect" (IREE) in a Bi/Ag interface, the charge current changes sign when reversing the order of the Ag and Bi stacking. This confirms the IREE nature of the conversion of spin into charge in these interfaces and opens the way to tailoring the spin sensing voltage by an appropriate trilayer sequence. V C 2015 AIP Publishing LLC.[http://dx.doi.org/10.1063/1.4919129] Classical spintronics relies on the generation and manipulation of spin polarized electrical currents in magnetic conductors. It has been recently understood that spin currents can also be generated in non-magnetic materials using the spin-orbit coupling (SOC) interaction opening a new field called spin-orbitronics. The best known of these is the Spin Hall Effect (SHE) first introduced in the seventies.1,2 It relies on a preferential directional scattering of electrons of different spins by SOC on crystalline imperfections. It thus results in the generation of a transverse spin current when a charge current flows in a large SOC material like, for instance, Pt. The inverse SHE (ISHE) has been widely used lately to sense a spin current as the SOC interaction converts it into a (transverse) charge current. Very recently, another SOC effect based on the Rashba interaction has been evidenced. It stems from the joint action of the SOC and built-in electric potentials in two-dimensional electron gases (2DEGs) existing at surfaces, interfaces, or semiconductor quantum wells. In these systems, a charge current generates a non-zero spin density and transverse spin accumulation 3,4 in virtue of the Rashba Hamiltonianwhere s is the spin vector, k is the momentum of charge carriers, z is the coordinate normal to the interface, and a R is the Rashba coefficient, proportional to the induced internal electric field. When in contact with a magnetic material, this spin density can apply a torque on the magnetization, a mechanism put forward to explain experimental results on current induced domain wall motion and magnetization switching. 5,6Recently, a related effect, the Inverse Rashba Edelstein Effect (IREE) has been demonstrated 7 where a spin current generated by ferromagnetic resonance (FMR) 8 in a magnetic layer, is converted into a charge current when flowing through an adjacent Ag/Bi interface. Bi (111) is indeed known to produce interface states with many materials where strong Rashba coupling takes place 9,10 and the Bi/Ag interface is known to be a particularly good one.7 Interestingly, because the asymmetrical potential at the interface is responsible for generating the transverse spin/charge density, one can envision to tailor the spin to charge conversion by shaping the asymmetric well. In particular, and quite straightforwardly, the charge current direction should be reversed when Ag/Bi is replaced by Bi/Ag, i.e., t...

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supporting

confidence: 82%

Control of the spin to charge conversion using the inverse Rashba-Edelstein effect

Sangiao

Teresa

Morellón

et al. 2015

Applied Physics Letters

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“…In the theoretical fitting, the spin Hall angle was estimated to be 0.00012, and is much smaller than that of Pt (0 .1 [21]), although the spin-orbit interaction of Bi is twice as large as that of Pt. In previous studies, the spin Hall angle of Bi was comparatively large (0.02 [13]), and the Bi was amorphous-like and the resistivity was one order of magnitude larger than that in the Bi of this study. The disorder in the amorphous Bi easily induced the Elliot-Yafet spin relaxation.…”

Section: Resultsmentioning

confidence: 99%

“…(1) resulting in a spin diffusion length to be approximately 20 nm at RT. In the previous study, the spin diffusion length of Bi on NiFe was estimated to be 8 nm [13];…”

Section: Resultsmentioning

confidence: 99%

“…Hence, a combination of electric spin conversion and resistivity measurements enables an understanding of the physics involving a correlation between spin and charge transport in semimetals. An example of the experimental demonstration of spin conversion in Bi is the ISHE [12,13], and these studies are motivated by the large SOI of Bi. Another notable study is the inverse Rashba-Edelstein effect (IREE) [14,15] appearing at a Bi/Ag interface, which has been attributed to a large Rashba splitting at the interface [16].…”

Section: Introductionmentioning

confidence: 99%

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Transport and spin conversion of multicarriers in semimetal bismuth

et al. 2016

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In this paper, we report on the investigation of (1) the transport properties of multi-carriers in semi-metal Bi and (2) the spin conversion physics in this semimetal system in a ferrimagnetic insulator, yttrium-iron-garnet. Hall measurements reveal that electrons and holes co-exist in the Bi, with electrons being the dominant carrier. The results of a spin conversion experiment corroborate the results of the Hall measurement; in addition, the inverse spin Hall effect governs the spin conversion in the semimetal/insulator system. This study provides further insights into spin conversion physics in semimetal systems.

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“…This would be the case if the spin current diffusing along the Cu channel was absorbed by the bulk Bi, instead of the interface. In such a scenario, however, the spin-diffusion length obtained from the SA experiment should be much longer, similar to the lengths obtained from WAL [32,34,35] or spin-pumping [11,36,37] measurements. Since this is not the case, the observed discrepancy could only be compatible with spin absorption in the bulk Bi by assuming a large spin-flip scattering at the interface, leading to spin memory loss (SML) [40].…”

mentioning

confidence: 96%

Origin of inverse Rashba-Edelstein effect detected at the Cu/Bi interface using lateral spin valves

et al. 2016

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The spin transport and spin-to-charge current conversion properties of bismuth are investigated using permalloy/copper/bismuth (Py/Cu/Bi) lateral spin valve structures. The spin current is strongly absorbed at the surface of Bi, leading to ultrashort spin-diffusion lengths. A spin-to-charge current conversion is measured, which is attributed to the inverse Rashba-Edelstein effect at the Cu/Bi interface. The spin-current-induced charge current is found to change direction with increasing temperature. A theoretical analysis relates this behavior to the complex spin structure and dispersion of the surface states at the Fermi energy. The understanding of this phenomenon opens novel possibilities to exploit spin-orbit coupling to create, manipulate, and detect spin currents in two-dimensional systems.

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Conversion of pure spin current to charge current in amorphous bismuth

Cited by 21 publications

References 25 publications

Control of the spin to charge conversion using the inverse Rashba-Edelstein effect

Control of the spin to charge conversion using the inverse Rashba-Edelstein effect

Transport and spin conversion of multicarriers in semimetal bismuth

Origin of inverse Rashba-Edelstein effect detected at the Cu/Bi interface using lateral spin valves

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