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藤本 純治*; 小椎八重 航*; 松尾 衛; 前川 禎通
Physical Review B, 103(22), p.L220402_1 - L220402_5, 2021/06
被引用回数：3 パーセンタイル：42.13(Materials Science, Multidisciplinary)The Dzyaloshinskii-Moriya interaction, i.e., antisymmetric exchange interaction, combined with a Zeeman magnetic field gives rise to various magnetic states such as chiral, helical, and skyrmionic states. This interaction conventionally originates from spin-orbit coupling and thus needs somewhat heavy elements. In contrast, we here show a Dzyaloshinskii-Moriya interaction which is driven by electric current vorticity. We also find that the vorticity acts on localized spins as a Zeeman field, which may explain a recent experiment on current-driven magnetic skyrmion creation and annihilation without an external magnetic field in a device with a notch structure in FeGe. The theory explains the control of skyrmion creation and annihilation by current direction and opens different possibilities for studies of magnetic textures by using structural settings.
小山 知弘*; 家田 淳一; 千葉 大地*
Applied Physics Letters, 116(9), p.092405_1 - 092405_5, 2020/03
被引用回数：3 パーセンタイル：25.71(Physics, Applied)The electric field (EF) modulation of magnetic domain wall (DW) creep velocity 
in Pt/Co/Pd structure with perpendicular magnetic anisotropy (MA) has been studied. The structures with different Co thickness 
up to 
nm are investigated. In all samples, applying a gate voltage induces a clear change in . Thicker samples provide a higher modulation efficiency, and the modulation magnitude of more than a factor of 100 times is observed in the thickest of 0.98 nm. The parameter characterizing the creep motion is significantly affected by the EF, resulting in the modulation of . Unlike the case, the MA modulation efficiency decreases with increasing . The present results are discussed based on the EF-induced change in the interfacial Dzyaloshinskii-Moriya interaction (iDMI), which has been recently demonstrated in the same structure, and dependence of the DW energy. The dependence of the modulation suggests that the EF effect on the iDMI is more important than the MA.
小山 知弘*; 仲谷 栄伸*; 家田 淳一; 千葉 大地*
Science Advances (Internet), 4(12), p.eaav0265_1 - eaav0265_5, 2018/12
被引用回数：43 パーセンタイル：88.96(Multidisciplinary Sciences)Pt/Co/Pd非対称構造において電場が磁壁速度を制御できることを示す。ゲート電圧を印加すると、50m/sまでの磁壁速度の著しい変化が観察され、これは以前の研究で観察されたものよりはるかに大きい。さらに、100m/sを超える磁壁速度の明確な変調も確認した。電場による界面のDzyaloshinskii-Moriya相互作用(DMI)の数パーセントまでの変化が、速度変調の原因であることがわかった。ここに示されているDMIを介した速度変化は、電場による異方性変調によって引き起こされるものとは根本的に異なるメカニズムである。本結果は、スピントロニクスデバイスの性能を向上させることができるDMI制御によるスピン構造とダイナミクスの電気的操作への道を開くものである。
