Zhang Yuxuan, Xu Teng, Jiang Wanjun, Yu Rong, Chen Zhen
School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China.
MOE Key Laboratory of Advanced Materials, Tsinghua University, Beijing 100084, China.
Nano Lett. 2024 Mar 6;24(9):2727-2734. doi: 10.1021/acs.nanolett.3c04409. Epub 2024 Feb 23.
Noncolinear spin textures, including chiral stripes and skyrmions, have shown great potential in spintronics. Basic configurations of spin textures are either Bloch or Néel types, and the intermediate hybrid type has rarely been reported. A major challenge in identifying hybrid spin textures is to quantitatively determine the hybrid angle, especially in ferrimagnets with weak net magnetization. Here, we develop an approach to quantify magnetic parameters, including chirality, saturation magnetization, domain wall width, and hybrid angle with sub-5 nm spatial resolution, based on Lorentz four-dimensional scanning transmission electron microscopy (Lorentz 4D-STEM). We find strong nanometer-scale variations in the hybrid angle and domain wall width within structurally and chemically homogeneous FeGd ferrimagnetic films. These variations fluctuate during different magnetization circles, revealing intrinsic local magnetization inhomogeneities. Furthermore, hybrid skyrmions can also be nucleated in FeGd films. These analyses demonstrate that the Lorentz 4D-STEM is a quantitative tool for exploring complex spin textures.
包括手性条纹和斯格明子在内的非共线自旋纹理在自旋电子学中已展现出巨大潜力。自旋纹理的基本构型要么是布洛赫型,要么是尼尔型,而中间的混合类型鲜有报道。识别混合自旋纹理的一个主要挑战是定量确定混合角,尤其是在净磁化强度较弱的亚铁磁体中。在此,我们基于洛伦兹四维扫描透射电子显微镜(Lorentz 4D-STEM)开发了一种方法,能够以亚5纳米的空间分辨率量化包括手性、饱和磁化强度、畴壁宽度和混合角在内的磁参数。我们发现在结构和化学性质均一的FeGd亚铁磁薄膜中,混合角和畴壁宽度存在强烈的纳米级变化。这些变化在不同的磁化循环中波动,揭示了固有的局部磁化不均匀性。此外,混合斯格明子也能在FeGd薄膜中形核。这些分析表明,Lorentz 4D-STEM是探索复杂自旋纹理的定量工具。
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