铁磁交换弹簧中的双曲布洛赫点
Hyperbolic Bloch points in ferrimagnetic exchange spring
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中文总结 AI 辅助
本研究通过X射线矢量磁断层扫描实验确定了铁磁三层结构中的布洛赫点构型，发现顶层因反铁磁耦合形成双曲构型，为布洛赫点工程提供了新路径。
中文摘要 AI 辅助
磁性材料中的布洛赫点在磁性信息传输方面具有吸引力。本文研究了磁性三层结构（$Gd_{12}Co_{88}/Nd_{17}Co_{83}/Gd_{24}Co_{76}$）中的布洛赫点构型，并通过实验确定。该结构在铁磁$Gd_{x}Co_{1-x}$合金中精心调整成分，以设计饱和磁化强度、交换长度和层间耦合（铁磁与反铁磁）。X射线矢量磁断层扫描使我们能够实验确定布洛赫点极性（与拓扑电荷相关）和布洛赫点螺旋度$γ$（由静磁能决定）。在底层（靠近铁磁界面），布洛赫点采用标准循环构型，螺旋度$γ$接近$π/2$。在顶层（饱和磁化强度低得多），布洛赫点在由反铁磁耦合产生的类奈尔交换弹簧畴壁内成核，并采用不常见的双曲构型，其特征是螺旋角大得多。我们的结果表明，在未来的应用中，通过调整材料参数和畴壁特性，为布洛赫点工程提供了一条路径。
英文摘要
Bloch points in magnetic materials are attractive entities in view of magnetic information transport. Here, Bloch point configuration has been investigated and experimentally determined in a magnetic trilayer ($Gd_{12}Co_{88}/Nd_{17}Co_{83}/Gd_{24}Co_{76}$) with carefully adjusted composition within the ferrimagnetic $Gd_{x}Co_{1-x}$ alloys in order to engineer saturation magnetization, exchange length, and interlayer couplings (ferromagnetic vs antiferromagnetic). X-ray vector magnetic tomography has allowed us to determine experimentally Bloch point polarity (related to topological charge) and Bloch point helicity $γ$ (determined by magnetostatic energy). At the bottom layer (close to the ferromagnetic interface), Bloch points adopt a standard circulating configuration with helicity $γ$ close to $π/2$. Within the top layer (with much lower saturation magnetization), Bloch points nucleate within a Neel-like exchange spring domain wall created by the antiferromagnetic coupling and adopt an uncommon hyperbolic configuration, characterized by much larger helicity angles. Our results indicate a path for Bloch point engineering in future applications adjusting material parameters and domain wall characteristics.
