We theoretically investigate a spin-mediated conversion from fluid dynamics to voltage, known as spin hydrodynamic generation (SHDG), in oscillatory and transient unsteady flows. We consider unsteady ...flows of liquid metal between two parallel infinite planes and then calculate its vorticity fields based on the Navier–Stokes equation for an incompressible viscous fluid. The spin accumulation and spin current generated by unsteady flows are derived using a spin-diffusion equation, including spin-vorticity coupling, which is a couple of angular momentum between electron spin and vorticity field in unsteady flows. The estimation of SHDG in liquid mercury flow suggests that an observable magnitude of voltage can be induced in unsteady flows. Our results are expected to enable the realization of high-speed spin devices with unsteady flows and broaden the range of fluid spintronics applicability.
•Theoretical investigation of spin-current generation by unsteady fluid dynamic.•The characteristic scales of unsteady flows crucial to spin-current generation are identified.•Unsteady flows can induce observable inverse spin Hall voltage.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The spin-motive force (SMF) in a simple ferromagnetic monolayer caused by a surface acoustic wave is studied theoretically via spin-vorticity coupling (SVC). The SMF has two mechanisms. The first is ...the SVC-driven SMF, which produces the first harmonic electromotive force, and the second is the interplay between the SVC and the magnetoelastic coupling, which produces the dc and second harmonic electromotive forces. We show that these electric voltages induced by a Rayleigh-type surface acoustic wave can be detected in polycrystalline nickel. No sophisticated device structures, noncollinear magnetic structures, or strong spin-orbit materials are used in our approach. Consequently, it is intended to broaden the spectrum of SMF applications considerably.
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CMK, CTK, FMFMET, IJS, NUK, PNG, UL, UM
Acoustic Rashba–Edelstein effect Funato, Takumi; Matsuo, Mamoru
Journal of magnetism and magnetic materials,
12/2021, Volume:
540
Journal Article
Peer reviewed
Open access
•Microscopic theory of the mechanical induction of the spin density.•Spin density driven by lattice acceleration and deformation of Rashba coupling.•High-efficient spin generation in Rashba systems ...with lattice distortion.
We theoretically study the mechanical induction of the spin density via the Rashba spin–orbit interaction (SOI). The spin density in the linear response to lattice distortion dynamics is calculated based on the microscopic theory. We reveal that there are two mechanisms of spin induction: one is the acoustic Edelstein effect (AEE) from the acceleration of the lattice dynamics and the other is caused by the Rashba spin–vorticity coupling (RSVC). We find that the AEE induces a more efficient spin-to-charge conversion in comparison with the conventional electric Edelstein effect. The induced spin density due to the RSVC can be attributed to the spatial symmetry breaking due to the Rashba SOI. Our work demonstrates high-efficiency spin generation in Rashba systems.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
In this article, the spin transfer between two ferromagnetic insulators is studied. There is a narrow gap between the ferromagnetic insulators so that they are weakly interacting with each other. One ...of the ferromagnetic insulators is moving at a constant speed while the other is at rest; hence, the system is out of equilibrium. In the presence of the shearing motion, the interaction amplitude is periodically modulated at the Doppler frequency. A unitary transformation allows us to regard the periodic modulation of the interaction amplitude as an effective potential, which drives the spin transfer. The amount of the spin current is controlled by the spectral overlap and the carrier population difference between the two ferromagnetic media. If the spectra of the two ferromagnets are moderately broadened, the overlap in the spectral domain increases, enlarging the spin current. However, too much broadening spoils the spectral overlap and, hence, the spin current. This implies that there is an optimal condition for maximizing the spin transfer.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
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