Breaking down the magnonic Wiedemann-Franz law in the hydrodynamic regime

Sano, Ryotaro*; Matsuo, Mamoru

Physical Review Letters, 130(16), p.166201_1 - 166201_7, 2023/04

https://doi.org/10.1103/PhysRevLett.130.166201

Direct and alternating magnon spin currents across a junction interface irradiated by linearly polarized laser

Nakata, Koki; Onuma, Yuichi*

Physical Review B, 105(14), p.144436_1 - 144436_7, 2022/04

https://doi.org/10.1103/PhysRevB.105.144436

Using a junction of the ferromagnetic insulators irradiated by linearly polarized laser, we propose a method for the generation of dc and ac spin currents of magnons across the junction interface, and provide an analytical formula for magnon transport induced by the inversion symmetry breaking.

Helicity current generation by distorted Rashba coupling

Funato, Takumi*; Matsuo, Mamoru

Physical Review B, 104(6), p.L060412_1 - L060412_5, 2021/08

https://doi.org/10.1103/PhysRevB.104.L060412

Universal -suppression of magnonic shot noise in diffusive insulating magnets

Nakata, Koki; Onuma, Yuichi*; Matsuo, Mamoru*

Physical Review B, 100(1), p.014406_1 - 014406_8, 2019/07

AA2019-0205.pdf:0.36MB

https://doi.org/10.1103/PhysRevB.100.014406

Extending a Boltzmann-Langevin theory to magnons, we show a universality of current-noise suppression in diffusive systems against the difference of quantum-statistical properties of bosons and fermions.

Spinmotive force

Ieda, Junichi; Maekawa, Sadamichi

Spin Current (2nd Edition), p.69 - 92, 2017/11

https://doi.org/10.1093/oso/9780198787075.003.0007

This chapter reviews spinmotive force (SMF), which is an emerging concept that is responsible for generating spin current and electric voltage in magnetic conductors. The SMF is induced in magnetic nanostructures via the exchange interaction between conduction spin and magnetization. Various types of the spin electric fields are found: adiabatic, nonadiabatic, and their spin-orbit coupled equivalents. In experiment, the adiabatic contributions with/without spin-orbit coupling have been observed whereas detecting nonadiabatic effects is challenging. The SMF offers electrical detection of magnetization dynamics, which would allow us to monitor the elusive dynamics of antiferromagnets.

Spin-transfer torques in antiferromagnetic textures; Efficiency and quantification method

Yamane, Yuta*; Ieda, Junichi; Sinova, J.*

Physical Review B, 94(5), p.054409_1 - 054409_8, 2016/08

AA2016-0164.pdf:0.5MB

https://doi.org/10.1103/PhysRevB.94.054409

We formulate a theory of spin-transfer torques in antiferromagnets, which covers the small to large limits of the exchange coupling energy relative to the kinetic energy of the inter-sublattice electron dynamics. Our theory suggests a natural definition of the efficiency of spin-transfer torques in antiferromagnets in terms of well-defined material parameters, revealing that the charge current couples predominantly to the antiferromagnetic order parameter and the sublattice-canting moment in, respectively, the limits of large and small exchange coupling. The effects can be quantified by analyzing the antiferromagnetic spin-wave dispersions in the presence of charge current: in the limit of large exchange coupling the spin-wave Doppler shift always occurs, whereas, in the opposite limit, the only spin-wave modes to react to the charge current are ones that carry a pronounced sublattice-canting moment. The findings offer a framework for understanding and designing spin-transfer torques in antiferromagnets belonging to different classes of sublattice structures such as, e.g., bipartite and layered antiferromagnets.

Mechanical generation of spin current

Harii, Kazuya; Matsuo, Mamoru; Takahashi, Ryo; Ono, Masao; Ieda, Junichi; Chudo, Hiroyuki; Okayasu, Satoru; Maekawa, Sadamichi; Saito, Eiji

no journal, , 

Spin current, a flow of spins, is a key concept in the field of spintronics. It is generated by using angular momentum conversion between magnetization, photon, electric current and so on. On the other hand, mechanical angular momentum due to mechanical motion has not been utilized for spin-current generation so far. In this talk, we discuss theoretical and experimental results for spin-current generation from mechanical motion. The spin-current generation by mechanical motion stems from the spin-rotation coupling, which is the fundamental interaction between spin angular momentum and rotational motion.

Spintronic micro-power generation

Ieda, Junichi

no journal, , 

Spintronics aims to harness both charge and spin degrees of freedom of electrons in condensed matter systems and opens fascinating new perspectives for both basic research and device technology. Cooperation of the spin-orbit interaction with the exchange interaction between the conduction electron spins and localized moment gives rise to a variety of phenomena that generate, control, and detect spin currents. In this talk, we present our contributions to developing new ways of micro-power generation based on spin currents, i.e., the spinmotive force, spin Seebeck effect, and spin hydrodynamic generation.

Neutron scattering study on YFeO under ultrasound irradiation

Shamoto, Shinichi; Matsuura, Masato*; Akatsu, Mitsuhiro*; Yasui, Yukio*; Ito, Takashi; Ieda, Junichi; Endo, Hitoshi*; Oda, Tatsuro*; Chang, L.-J.*; Nemoto, Yuichi*; et al.

no journal, , 

no abstracts in English

Quantum spin-current noise of magnons

Nakata, Koki; Onuma, Yuichi*; Matsuo, Mamoru*

no journal, , 

Using the Keldysh formalism, we calculate a magnonic current-noise and compare it with the current-noise of electrically charged electrons. We thus discuss the universality of current-noise against the difference of quantum-statistical properties of bosons and fermions.