2025-10-20 東北大学
図1. (a) Pt / Co / Ir / Co / Pt人工反強磁性体の積層構造の模式図および期待されるカー顕微鏡像のコントラスト。(b)細線に対し電流を左から右に流した場合と、右から左に流した場合のカー顕微鏡像。白い矢印が磁壁位置を示しており、パルス状の電流の印加回数（1回目から5回目）に依存して磁壁位置が移動している様子がわかる。
＜関連情報＞
- https://www.tohoku.ac.jp/japanese/2025/10/press20251020-02-torque.html
- https://www.tohoku.ac.jp/japanese/newimg/pressimg/tohokuuniv-press20251020_01web_torque.pdf
- https://advanced.onlinelibrary.wiley.com/doi/10.1002/advs.202514598
合成反強磁性体における二重スピン軌道トルクによる磁壁の効率的な操作 Efficient Manipulation of Magnetic Domain Wall by Dual Spin-Orbit Torque in Synthetic Antiferromagnets
Hiroto Masuda, Yuta Yamane, Takaaki Dohi, Takumi Yamazaki, Rajkumar Modak, Ken-ichi Uchida, Jun’ichi Ieda, Mathias Kläui, Koki Takanashi, Takeshi Seki
Advanced Science Published: 17 October 2025
DOI:https://doi.org/10.1002/advs.202514598
Abstract
Current-induced domain-wall motion (CIDWM) in a synthetic antiferromagnet is a key phenomenon for developing potential high-density-packed magnetic domain-wall memory with fast operation. Here, CIDWM is reported in the antiferromagnetically-coupled two Co layers through the Ir interlayer sandwiched by the two Pt layers: Pt/Co/Ir/Co/Pt. The top and bottom Pt layers play a role for generating the spin current coming from the spin Hall effect, which gives rise to the dual spin-orbit torque (SOT) acting on the perpendicular magnetizations of the Co layers. Although a simple argument would predict that SOTs from top and bottom Pt layers cancel each other out, the dual SOT nucleates a reversed magnetic domain and drives the CIDWM effectively at current density of the order of 1011 A m−2. This study also examines the effect of antisymmetric interlayer exchange coupling (AIEC) on CIDWM. A positive correlation between the magnitude of AIEC and the domain wall velocity is found, whereas the current density required for nucleating the reversed domain shows a negative correlation with the magnitude of AIEC. These facts suggest that the existence of AIEC improves the performance of CIDWM. The present results provide a new avenue to design SOT domain wall devices based on a synthetic antiferromagnet.
