船戸 匠 (フナト タクミ)

Funato, Takumi

写真a

所属(所属キャンパス)

研究所・センター等 グローバルリサーチインスティテュート (三田)

職名

特任助教(有期)

外部リンク

学歴 【 表示 / 非表示

  • 2018年04月
    -
    2021年03月

    名古屋大学, 理学研究科, 物質理学専攻(物理系)

    大学院, 修了, 博士後期

 

論文 【 表示 / 非表示

  • Acoustic Rashba–Edelstein effect

    Funato T., Matsuo M.

    Journal of Magnetism and Magnetic Materials (Journal of Magnetism and Magnetic Materials)  540 2021年12月

    ISSN  03048853

     概要を見る

    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.

  • Helicity current generation by distorted Rashba coupling

    Funato T., Matsuo M.

    Physical Review B (Physical Review B)  104 ( 6 )  2021年08月

    ISSN  24699950

     概要を見る

    We theoretically study spin transport in two- or three-dimensional Rashba systems dynamically distorted by surface acoustic waves. The spin currents in the linear response to lattice distortion dynamics are calculated on the basis of a microscopic theory combined with local coordinate transformations. As a result, we find a mechanism of direct spin-current generation from lattice distortion not associated with a charge current or spin accumulation. Moreover, the in-plane helicity currents are generated by shear surface acoustic waves via the present mechanism. The generated helicity currents are not parallel to the vorticity of the lattice, and cannot be created with the conventional methods. Thus, our findings offer an alternative functionality of the conventional Rashba systems in the field of spintronics.

  • Acoustic spin Hall effect in strong spin-orbit metals

    Kawada T., Kawaguchi M., Funato T., Kohno H., Hayashi M.

    Science Advances (Science Advances)  7 ( 2 )  2021年01月

     概要を見る

    We report on the observation of the acoustic spin Hall effect that facilitates lattice motion-induced spin current via spin-orbit interaction (SOI). Under excitation of surface acoustic wave (SAW), we find that a spin current flows orthogonal to the SAW propagation in nonmagnetic metals (NMs). The acoustic spin Hall effect manifests itself in a field-dependent acoustic voltage in NM/ferromagnetic metal bilayers. The acoustic voltage takes a maximum when the NM layer thickness is close to its spin diffusion length, vanishes for NM layers with weak SOI, and increases linearly with the SAW frequency. To account for these results, we find that the spin current must scale with the SOI and the time derivative of the lattice displacement. These results, which imply the strong coupling of electron spins with rotating lattices via the SOI, show the potential of lattice dynamics to supply spin current in strong spin-orbit metals.

  • Extrinsic spin Hall effect in inhomogeneous systems

    Funato T., Kohno H.

    Physical Review B (Physical Review B)  102 ( 9 )  2020年09月

    ISSN  24699950

     概要を見る

    Charge-to-spin conversion in inhomogeneous systems is studied theoretically. We consider free electrons subject to impurities with spin-orbit interaction and with spatially modulated distribution, and calculate spin accumulation and spin current induced by an external electric field. It is found that the spin accumulation is induced by the vorticity of electron flow through side-jump and skew-scattering processes, and the differences of the two processes are discussed. The results can be put in a form of a generalized spin diffusion equation with a spin source term given by the divergence of the spin Hall current. This spin source term reduces to the form of spin-vorticity coupling when the spin Hall angle is independent of impurity concentration. We also study the effects of long-range Coulomb interaction, which is indispensable when the process involves charge inhomogeneity and accumulation as in the present problem.

  • Generation of spin current from lattice distortion dynamics: Spin–orbit routes

    Funato T., Kohno H.

    Journal of the Physical Society of Japan (Journal of the Physical Society of Japan)  87 ( 7 )  2018年

    ISSN  00319015

     概要を見る

    Generation of spin current from lattice distortion dynamics in metals is studied with special attention on the effect of spin–orbit coupling. Treating the lattice distortion by local coordinate transformation, we calculate spin current and spin accumulation with the linear response theory. It is found that there are two routes to the spin–current generation: one via the spin Hall effect and the other via the spin accumulation. The present effect due to spin–orbit coupling can be comparable to, or even larger than, the one based on the spin–vorticity coupling in systems with strong spin–orbit coupling.

競争的研究費の研究課題 【 表示 / 非表示

  • 静的歪み構造を利用したスピン流生成機構の微視的解析

    2021年08月
    -
    2023年03月

    文部科学省・日本学術振興会, 科学研究費助成事業, 船戸 匠, 研究活動スタート支援, 補助金,  研究代表者