Next-generation concepts for solid-state memory devices are based on current-driven domain wall propagation, where the wall velocity governs the device performance. It has been shown that the domain wall velocity and the direction of travel is controlled by the nature of the wall and its chirality. This chirality is attributed to effects emerging from the lack of inversion symmetry at the interface between a ferromagnet and a heavy metal, leading to an interfacial Dzyaloshinskii-Moriya interaction that can control the shape and chirality of the magnetic domain wall. Here we present direct imaging of domain walls in Pt/Co/AlO$_x$ films using Lorentz transmission electron microscopy, demonstrating the presence of homochiral, and thus topologically protected, Néel walls. Such domain walls are good candidates for dense data storage, bringing the bit size down close to the limit of the domain wall width.
Dynamics of domain growth driven by dipolar interactions in a perpendicularly magnetized ultrathin film
对垂直磁化的Fe/2 ML Ni/W（110）双金属薄膜的交流磁化率的测量表明，该系统支持的条纹状畴结构中畴生长和畴密度变化的动力学特征是清晰的。在0.20 K/s < R < 0.70 K/s范围内，随着升温速率的增加，磁化率峰向高温移动。使用松弛模型的分析表明，定量的动力学驱动的非平衡域密度在（近）零场（即偶极相互作用），和温度的变化是由于响应时间由局部域壁段的钉扎结构缺陷。由偶极相互作用驱动的畴密度弛豫的基本时间尺度比由外加场驱动的单个巴克豪森步骤的基本时间尺度慢10^5倍。基本时间尺度的增加反映了偶极子和塞曼能量的相对大小，以及需要许多局部畴壁段的相关运动来影响畴生长。
Tailoring Ultrathin Magnetic Multilayers at Terraced Topologically Insulating Interfaces for Perpendicularly Magnetized Domains
University of Leeds（利兹大学）；ISIS Neutron and Muon Source, STFC Rutherford Appleton Laboratory（STFC卢瑟福阿普尔顿实验室中子与μ子源）；Diamond Light Source（钻石光源）；Imperial College London（伦敦帝国理工学院）
Perpendicularly magnetized YIG films with small Gilbert damping constant and anomalous spin transport properties
具有垂直磁各向异性（PMA）的Y3 Fe 5 O 12（YIG）薄膜在自旋电子学领域的应用近年来引起了人们的广泛关注。本文报道了在（Gd2.6Ca0.4）（Ga4.1Mg0.25Zr0.65）O 12（SGGG）衬底上外延生长的YIG薄膜在未经预处理的情况下产生的PMA。倒易空间映射表明，薄膜晶格匹配的衬底没有应变弛豫。通过铁磁共振和极化中子反射测量，我们发现这些YIG薄膜具有超低的Gilbert阻尼常数，在YIG/SGGG界面处的磁死层厚度约为0.3nm。此外，与Pt/YIG/Gd 3Ga 5 O 12（GGG）薄膜相比，Pt/YIG/SGGG薄膜的输运行为显示出自旋混合电导的增强和反常霍尔效应的非单调磁场依赖性.在150 ~ 350 K的温度范围内提取了非单调的反常霍尔信号，这可能是由于单轴应变在Pt/YIG界面上产生的非共线磁序引起的.
Cryogenic-temperature Grain-to-grain Epitaxial Growth of High-quality Ultrathin CoFe Layer on MgO Tunnel Barrier for High-performance Magnetic Tunnel Junctions
