Castro I, Riveros A, Palma J L, Abelmann L, Tomasello R, Rodrigues D R, Giordano A, Finocchio G, Gallardo R A, Vidal-Silva N
Departamento de Ciencias Físicas, Universidad de La Frontera, Casilla 54-D, 4811186, Temuco, Chile.
Centro de Investigación en Ingeniería de Materiales, FINARQ, Universidad Central de Chile, Avda. Santa Isabel 1186, 8330601, Santiago, Chile.
Sci Rep. 2025 Apr 8;15(1):11944. doi: 10.1038/s41598-025-95584-9.
In this work, we explored theoretically the spatial resolution of magnetic solitons and the variations of their sizes when subjected to a magnetic force microscopy (MFM) measurement. Next to tip-sample separation, we considered reversal in the magnetization direction of the tip, showing that the magnetic soliton size measurement can be strongly affected by the magnetization direction of the tip. In addition to previous studies that only consider thermal fluctuations, we developed a theoretical method to obtain the minimum observable length of a magnetic soliton and its length variation due to the influence of the MFM tip by minimizing the soliton's magnetic energy. We show that a simple spherical model for the MFM tip can capture most of the physics underlying tip-sample interactions, with the key requirement being an estimate of the magnetization field within the sample. Our model uses analytical and numerical calculations and prevents overestimating the characteristic length scales from MFM images. We compared our method with available data from MFM measurements of domain wall widths, and we performed micromagnetic simulations of a skyrmion-tip system, finding a good agreement for both attractive and repulsive domain wall profile signals and for the skyrmion diameter in the presence of the magnetic tip. In addition, the theoretically calculated frequency shift presents good qualitative agreement with experimental measurements. Our results provide significant insights for a better interpretation of MFM measurements of different magnetic solitons and will be helpful in the design of potential reading devices based on magnetic solitons as information carriers.
在这项工作中，我们从理论上探究了磁孤子的空间分辨率以及在进行磁力显微镜（MFM）测量时其尺寸的变化。除了针尖 - 样品间距外，我们还考虑了针尖磁化方向的反转，结果表明磁孤子尺寸测量会受到针尖磁化方向的强烈影响。除了以往仅考虑热涨落的研究外，我们还开发了一种理论方法，通过最小化孤子的磁能来获得磁孤子的最小可观测长度及其因MFM针尖影响而产生的长度变化。我们表明，MFM针尖的简单球形模型能够捕捉针尖 - 样品相互作用背后的大部分物理原理，关键要求是估计样品内部的磁化场。我们的模型采用解析和数值计算，避免了从MFM图像中高估特征长度尺度。我们将我们的方法与来自畴壁宽度MFM测量的现有数据进行了比较，并对斯格明子 - 针尖系统进行了微磁模拟，发现在存在磁针尖的情况下，对于吸引和排斥畴壁轮廓信号以及斯格明子直径都有很好的一致性。此外，理论计算的频移与实验测量结果在定性上具有良好的一致性。我们的结果为更好地解释不同磁孤子的MFM测量提供了重要见解，并将有助于设计基于磁孤子作为信息载体的潜在读取设备。
