Stabilization of exponential number of discrete remanent states with localized spin-orbit torques
Shubhankar Das, Ariel Zaig, Moty Schultz, Lior Klein
备注：
5 pages, 4 Figures; The following article has been accepted by Applied Physics Letters. After it is published, it will be found at https://aip.scitation.org/journal/apl
利用双层膜$β$/Ni $_{0.8}$ Fe $_{0.2}$，我们制备了由两个、三个和四个交叉椭圆组成的结构，在交叉区域分别表现出形状诱导的双轴、三轴和四轴磁各向异性。由N个交叉椭圆组成的结构可以通过施加（和去除）外部磁场而稳定在2N个回复态。然而，我们表明，与无场自旋轨道力矩引起的流动电流在个别椭圆，reflux状态的数量增长到2 $^\text{N}$。此外，当电流在不同椭圆的边缘之间流动时，剩余状态的数量跳到2个$^\text{2N}$，包括在重叠区域中呈现$π$ -Néel畴壁的状态。相对简单的磁性结构所表现出的大量可访问的rexeries磁状态为包括存储器件在内的有趣的自旋电子学应用铺平了道路。
英文摘要：
Using bilayer films of $β$-Ta/Ni$_{0.8}$Fe$_{0.2}$, we fabricate structures consisting of two, three and four crossing ellipses which exhibit shape-induced bi-axial, tri-axial and quadro-axial magnetic anisotropy in the crossing area, respectively. Structures consisting of N crossing ellipses can be stabilized in 2N remanent states by applying (and removing) an external magnetic field. However, we show that with field-free spin-orbit torques induced by flowing currents in individual ellipses, the number of remanent states grows to 2$^\text{N}$. Furthermore, when the current flows between the edges of different ellipses the number of remanent states jumps to 2$^\text{2N}$, including states which exhibit a $π$-Néel domain wall in the overlap area. The very large number of accessible remanent magnetic states that are exhibited by the relatively simple magnetic structures paves the way for intriguing spintronics applications including memory devices.
Commensuration torques in double-moiré twisted trilayer hexagonal boron nitride and graphene heterostructures
University of Seoul（首尔大学）；Sungkyunkwan University（成均馆大学）；Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST（加泰罗尼亚纳米科学与技术研究所（ICN2，西班牙高等科学研究委员会和巴塞罗那独立科学研究所））
College of Engineering Physics, Shenzhen Technology University（深圳技术大学工程物理学院）；The Center for Advanced Quantum Studies and Department of Physics, Beijing Normal University（北京师范大学高级量子研究中心及物理系）；College of New Materials and New Energies, Shenzhen Technology University（深圳技术大学新材料与新工程学院）；Department of Applied Physics, Waseda University（早稻田大学应用物理系）；Anhui Province Key Laboratory of Low-Energy Quantum Materials and Devices, High Magnetic Field Laboratory, HFIPS, Chinese Academy of Sciences（中国科学院合肥物质科学研究院强磁场科学中心低能量子材料与器件安徽省重点实验室）；School of Science and Engineering, The Chinese University of Hong Kong, Shenzhen（香港中文大学（深圳）理学院）
Current-driven dynamics and ratchet effect of skyrmion bubbles in a ferrimagnetic insulator
磁skyrmions是一种紧凑的手性自旋织构，具有丰富的拓扑现象，并具有开发高密度存储器件和由自旋电流驱动的新型计算方案的潜力。在这里，我们展示了室温下的界面稳定性和电流驱动的控制skyrmion气泡的亚铁磁绝缘体Tm 3Fe 5 O 12（TmIG）耦合到Pt。我们跟踪电流引起的运动的个别skyrmion气泡。晶体的亚铁磁有序性以及自旋-轨道矩和钉扎的相互作用决定了TmIG中的skyrmion动力学，并导致以负偏转角和跳跃运动为特征的强skyrmion霍尔效应。此外，我们表明，速度和脱钉阈值的skyrmion气泡可以修改交换耦合TmIG的面内磁化Y3 Fe 5 O 12层，扭曲的自旋纹理的skyrmion，并导致其动态方向相关的整流。这种效应相当于一个磁性棘轮，被用来控制一个类似跑道的装置中的skyrmion流。
