Zhou, W.*; Seki, Takeshi*; Imamura, Hiroshi*; Ieda, Junichi; Takanashi, Koki*
Physical Review B, 100(9), p.094424_1 - 094424_5, 2019/09
Yamanouchi, Michihiko*; Oyamada, Tatsuro*; Sato, Koichi*; Ota, Hiromichi*; Ieda, Junichi
IEEE Transactions on Magnetics, 55(7), p.1400604_1 - 1400604_4, 2019/07
Hoshasen To Sangyo, (146), p.48 - 52, 2019/06
no abstracts in English
JPSJ News and Comments (Internet), 16, P. 12_1, 2019/01
Koyama, Tomohiro*; Nakatani, Yoshinobu*; Ieda, Junichi; Chiba, Daichi*
Science Advances (Internet), 4(12), p.eaav0265_1 - eaav0265_5, 2018/12
We show that the electric field (EF) can control the magnetic domain wall (DW) velocity in a Pt/Co/Pd asymmetric structure. With the application of a gate voltage, a significant change in DW velocity up to 50 m/s is observed, which is much greater than that observed in previous studies. Moreover, a DW velocity exceeding 100 m/s is clearly modulated. An EF-induced change in the interfacial Dzyaloshinskii-Moriya interaction (DMI) up to several percent is found to be the origin of the velocity modulation. The DMI-mediated velocity change shown here is a fundamentally different mechanism from that caused by EF-induced anisotropy modulation. Our results will pave the way for the electrical manipulation of spin structures and dynamics via DMI control, which can enhance the performance of spintronic devices.
Yamane, Yuta*; Ieda, Junichi
Magune, 13(5), p.235 - 241, 2018/10
Ieda, Junichi; Barnes, S. E.*; Maekawa, Sadamichi
Journal of the Physical Society of Japan, 87(5), p.053703_1 - 053703_4, 2018/05
Ieda, Junichi; Maekawa, Sadamichi
Spin Current (2nd Edition), p.69 - 92, 2017/11
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.
Yamane, Yuta*; Ieda, Junichi; Sinova, J.*
Physical Review B, 94(5), p.054409_1 - 054409_8, 2016/08
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.
Yamane, Yuta*; Ieda, Junichi; Sinova, J.*
Physical Review B, 93(18), p.180408_1 - 180408_5, 2016/05
Takahashi, Ryo*; Matsuo, Mamoru; Ono, Masao; Harii, Kazuya; Chudo, Hiroyuki; Okayasu, Satoru; Ieda, Junichi; Takahashi, Saburo*; Maekawa, Sadamichi; Saito, Eiji
Nature Physics, 12, p.52 - 56, 2016/01
Ono, Masao; Chudo, Hiroyuki; Harii, Kazuya; Okayasu, Satoru; Matsuo, Mamoru; Ieda, Junichi; Takahashi, Ryo*; Maekawa, Sadamichi; Saito, Eiji
Physical Review B, 92(17), p.174424_1 - 174424_4, 2015/11
Haku, Satoshi*; Tashiro, Takaharu*; Nakayama, Hiroyasu*; Ieda, Junichi; Entani, Shiro; Sakai, Seiji; Ando, Kazuya*
Applied Physics Express, 8(7), p.073009_1 - 073009_3, 2015/07
We found that the spin pumping in a NiFe/Pt bilayer is strongly suppressed by inserting single-layer graphene (SLG) at the interface. The spin pumping in the NiFe/Pt bilayer enhances the magnetization damping of the ferromagnetic layer, which is quantified from microwave frequency dependence of ferromagnetic resonance linewidth. We show that the enhancement of the magnetization damping due to the spin pumping disappears in a NiFe/SLG/Pt trilayer. This result indicates that the spin pumping is blocked by the atomic monolayer, demonstrating the crucial role of the interfacial short-range spin-exchange coupling in the spin pumping in metallic systems.
Fukami, Shunsuke*; Ieda, Junichi; Ono, Hideo*
Physical Review B, 91(23), p.235401_1 - 235401_7, 2015/06
We study thermal stability of a magnetic domain wall pinned in nanowires made of Co/Ni multilayers, and analyze the effective volume that governs the thermal stability. We find that, above a critical wire width, the domain wall depinning is initiated by a subvolume excitation and that the critical width is dependent on the wire thickness. The obtained findings are supported by the distribution of critical current density for domain wall depinning and are qualitatively described by considering the balance between the Zeeman energy and domain wall elastic energy.
Harii, Kazuya; Chudo, Hiroyuki; Ono, Masao; Matsuo, Mamoru; Ieda, Junichi; Okayasu, Satoru; Maekawa, Sadamichi; Saito, Eiji
Japanese Journal of Applied Physics, 54(5), p.050302_1 - 050302_3, 2015/05
Chudo, Hiroyuki; Harii, Kazuya; Matsuo, Mamoru; Ieda, Junichi; Ono, Masao; Maekawa, Sadamichi; Saito, Eiji
Journal of the Physical Society of Japan, 84(4), p.043601_1 - 043601_4, 2015/04
Matsuo, Mamoru; Ieda, Junichi; Maekawa, Sadamichi
Kotai Butsuri, 49(11), p.611 - 625, 2014/11
no abstracts in English
Yamane, Yuta*; Hemmatiyan, S.*; Ieda, Junichi; Maekawa, Sadamichi; Sinova, J.*
Scientific Reports (Internet), 4, p.6901_1 - 6901_5, 2014/11
Interaction between local magnetization and conduction electrons is responsible for a variety of phenomena in magnetic materials. It has been recently shown that spin current and associated electric voltage can be induced by magnetization that depends on both time and space. This effect, called spinmotive force, provides for a powerful tool for exploring the dynamics and the nature of magnetic textures, as well as a new source for electromotive force. Here we theoretically demonstrate the generation of electric voltages in magnetic bubble array systems subjected to a magnetic field gradient. It is shown by deriving expressions for the electric voltages that the present system offers a direct measure of phenomenological parameter that describes non-adiabaticity in the current induced magnetization dynamics. This spinmotive force opens a door for new types of spintronic devices that exploit the field-gradient.
Ieda, Junichi; Matsuo, Mamoru; Maekawa, Sadamichi
Solid State Communications, 198, p.52 - 56, 2014/11