Gen Tatara

RIKEN Center for Emergent Matter Science

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Co-Authors

Hiroshi Kohno

Kure Medical Center

Junya Shibata

Toyo University

Akihito Takeuchi

Aoyama Gakuin University

Hidetoshi Fukuyama

Tokyo University of Science

Katsuhisa Taguchi

Hiroshima University

Kazuhiro Hosono

National Institute for Materials Science

Collins Ashu Akosa

Waseda University

Y. Otani

The University of Tokyo

H. Kohno

Kure Medical Center

Noriyuki Nakabayashi

Tokyo Metropolitan University

Cooperative Institutions

The University of Tokyo

Tohoku University

RIKEN Center for Emergent Matter Science

Japan Science and Technology Agency

Osaka University

Kyoto University

RIKEN

Spintronics Research Network of Japan

National Institute of Advanced Industrial Science and Technology

Centre National de la Recherche Scientifique

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Role of magnetic monopole in current generation from magnetization dynamics

The Japan Society of Applied Physics (2013)

Gen Tatara

Magnetization dynamics

Dynamics

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Citations (0)

Anomalous Hall Effect and Skyrmion Number in Real and Momentum Spaces

Journal of the Physical Society of Japan (2004)

Masaru Onoda Gen Tatara Naoto Nagaosa

We study the anomalous Hall effect (AHE) for the double exchange model with the exchange coupling $|J_H|$ being smaller than the bandwidth $|t|$ for the purpose of clarifying the following unresolved and confusing issues: (i) the effect of the underlying lattice structure, (ii) the relation between AHE and the skyrmion number, (iii) the duality between real and momentum spaces, and (iv) the role of the disorder scatterings; which is more essential, $\sigma_H$ (Hall conductivity) or $\rho_H$ (Hall resistivity)? Starting from a generic expression for $\sigma_H$, we resolve all these issues and classify the regimes in the parameter space of $J_H \tau$ ($\tau$: elastic-scattering time), and $\lambda_{s}$ (length scale of spin texture). There are two distinct mechanisms of AHE; one is characterized by the real-space skyrmion-number, and the other by momentum-space skyrmion-density at the Fermi level, which work in different regimes of the parameter space.

Skyrmion

Lattice (music)

Duality (order theory)

Momentum (technical analysis)

10.1143/jpsj.73.2624

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Citations (128)

Effective Hamiltonian Approach to Optical Activity in Weyl Spin–Orbit System

Journal of the Physical Society of Japan (2018)

Hideo Kawaguchi Gen Tatara

Chirality or handedness in condensed matter induces anomalous optical responses such as natural optical activity, rotation of the plane of light polarization, as a result of breaking of spatial-inversion symmetry. In this study, optical properties of a Weyl spin-orbit system with quadratic dispersion, a typical chiral system invariant under time-reversal, are investigated theoretically by deriving an effective Hamiltonian based on an imaginary-time path-integral formalism. We show that the effective Hamiltonian can be indeed written in terms of an optical chirality order parameter suggested by Lipkin. The natural optical activity is discussed based on the Hamiltonian.

Hamiltonian (control theory)

Orbit (dynamics)

10.7566/jpsj.87.064002

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Citations (3)

Topological aspect of chirality-induced Hall conductivity in the perturbative regime

Journal of Magnetism and Magnetic Materials (2004)

Gen Tatara M. Yamanaka Masaru Onoda

Chirality

Hall conductivity

10.1016/j.jmmm.2003.12.170

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Citations (2)

Nucleation and dynamics of magnetic vortices under spin-polarized current

Physical Review B (2008)

Y. Nakatani Junya Shibata Gen Tatara Hiroshi Kohno A. Thiaville

Spin-polarized current in a ferromagnet is known to lead to the instability of the uniformly magnetized state. In this paper, it is demonstrated by micromagnetic simulations that, in films or wide wires, the above instability is followed by the formation of magnetic vortices. Subsequent magnetization dynamics is also studied in terms of vortices, which includes pair dynamics and pair annihilation. Using a simple analytical model that considers the vortices as points, the dynamics of two interacting vortices under the current is classified according to their vorticity and polarity. This explains well the essential features of the simulation results.

Polarity (international relations)

Vortex state

Dynamics

Magnetization dynamics

10.1103/physrevb.77.014439

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Citations (26)

Publisher's Note: Spin motive force induced by Rashba interaction in the strongsdcoupling regime [Phys. Rev. B87, 054403 (2013)]

Physical Review B (2013)

Gen Tatara Noriyuki Nakabayashi Kyung‐Jin Lee

10.1103/physrevb.88.219901

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Citations (2)

Topological Hall signatures of magnetic hopfions

Physical Review Research (2020)

Börge Göbel Collins Ashu Akosa Gen Tatara Ingrid Mertig

The authors calculate the topological Hall conductivity of electrons in a magnetic hopfion. This nano-object is a noncollinear spin texture that gives rise to a locally uncompensated emergent magnetic field. Due to this field, a hopfion exhibits a distinct topological Hall signature that can be useful for spintronic applications. One simulated example is a mechanism for detecting hopfions in racetrack data storage devices.

Signature (topology)

Texture (cosmology)

10.1103/physrevresearch.2.013315

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Citations (43)

Hydrodynamic theory of vorticity-induced spin transport

arXiv (Cornell University) (2021)

Gen Tatara

Electron spin transport in a disordered metal is theoretically studied from the hydrodynamic viewpoint focusing on the role of electron vorticity. The spin-resolved momentum flux density of electrons is calculated taking account of the spin-orbit interaction and uniform magnetization, and the expression for the spin motive force is obtained as the linear response to a driving electric field. It is shown that the spin-resolved momentum flux density and motive force are characterized by troidal moments expressed as vector products of the applied external electric field and the spin polarization and/or magnetization. The spin-vorticity and magnetization-vorticity couplings studied recently are shown to arise from the toridal moments contribution to the momentum flux density. Spin motive force turns out to have a nonconservative contribution besides the conventional conservative one due to the spin-vorticity coupling. Spin accumulation induced by an electric field is calculated to demonstrate the direct relation between vorticity and induced spin, and the spin Hall effect is interpreted as due to the spin-vorticity coupling. The spin-vorticity coupling is shown to give rise to a vorticity-induced torque and a spin relaxation. The vorticity-induced torque is a linear effect of the spin-orbit interaction and is expected to be larger than the second-order torques such as nonadiabatic ($\beta$) current-induced torque due to magnetization structure. The intrinsic inverse spin Hall effect is argued to correspond to the antisymmetric components of the momentum flux density in the hydrodynamic context.

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Nonlocal spin-charge conversion via Rashba spin-orbit interaction

Physical review. B./Physical review. B (2019)

Junji Fujimoto Gen Tatara

We show theoretically that conversion between spin and charge by spin-orbit interaction in metals occurs even in a nonlocal setup where magnetization and spin-orbit interaction are spatially separated if electron diffusion is taken into account. Calculation is carried out for the Rashba spin-orbit interaction treating the coupling with a ferromagnet perturbatively. The results indicate the validity of the concept of effective spin gauge field (spin motive force) in the nonlocal configuration. The inverse Rashba-Edelstein effect observed for a trilayer of a ferromagnet, a normal metal and a heavy metal can be explained in terms of the nonlocal effective spin gauge field.

Spin–orbit interaction

Rashba effect

Orbit (dynamics)

10.1103/physrevb.99.054407

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Citations (8)

Suppression of vortex motion in La1.85Sr0.15CuO4 with the splayed configuration of columnar defects

Physica C Superconductivity (1997)

Xiying Fan M. Terasawa T. Mitamura T. Kohara K. Ueda

Motion picture

10.1016/s0921-4534(97)01167-2

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Citations (3)