Study to elucidate a driving mechanism of moving magnetic skyrmions in a nonequilibrium steady state and under an external field

2019 Fiscal Year Final Research Report

• Project/Area Number: 17K14327
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Condensed matter physics II
• Research Institution: Tohoku University
• Principal Investigator: Daisuke Okuyama 東北大学, 多元物質科学研究所, 助教 (30525390)
• Project Period (FY): 2017-04-01 – 2020-03-31
• Keywords: 非平衡定常状態の物理 / 中性子散乱 / 磁気スキルミオン

Outline of Final Research Achievements

To elucidate a nonequilibrium steady state of a magnetic skyrmion lattice under an external force, we study a small angle neutron diffraction experiment of typical chiral magent MnSi under an electric current flow. In our study, the deformation of the moving magnetic skyrmion lattice in MnSi under electric current flow observed. A spatially inhomogeneous rotation of the skyrmion lattice, with an inverse rotation sense for opposite sample edges, is observed for current densities greater than a threshold value jt ~ 1 MA/m2. Our result show that skyrmion lattices under current flow experience significant friction near the sample edges due to pinning and locally deforms like plastic matter when driven under electric current. This plastic deformation of the magnetic skyrmion lattice is a critical effect that must be considered for anticipated skyrmion-based applications at the nanoscale.

Free Research Field

磁性、固体物理

Academic Significance and Societal Importance of the Research Achievements

今回得られた研究結果より、外力によって駆動している磁気スキルミオン格子は試料端でのピニング効果により摩擦のような力を受け塑性変形を起こすことが分かった。駆動中の塑性変形はこれまで行われてきた磁気スキルミオン研究では考慮されず、薄膜や細線等のデバイスとして磁気スキルミオンを利用する際にバルク試料と異なった性質を示す一因になっているのではと予想する。本研究成果は磁気スキルミオンを使った記憶媒体などを実現するのに必要不可欠な新しい知見を示したため、本研究の波及効果は大きいと考えている。