由高阶相互作用稳定的具有任意拓扑电荷的亚20纳米自旋织构
Sub-20 nm spin textures with arbitrary topological charge stabilized by higher-order interactions
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中文总结 AI 辅助
本研究通过第一性原理参数化的原子自旋模型，预测了Janus单层中由高阶自旋相互作用稳定的亚20纳米高拓扑电荷自旋织构，揭示了其成核与稳定机制。
中文摘要 AI 辅助
拓扑磁化织构在现代磁学中扮演着核心角色。对于许多应用而言，同一系统中具有不同拓扑电荷$Q$的自旋织构尤其具有吸引力。尽管在反演对称磁体中已报道了斯格明子与反斯格明子（$|Q| = 1$）的共存，但将其扩展到具有任意电荷的高$Q$（$|Q| > 1$）织构仍然难以实现。在此，我们利用由第一性原理计算参数化的原子级自旋模型，预测了在Janus单层——一类日益受关注的范德华磁体——中亚20纳米高$Q$织构的出现。我们探索了$|Q|$高达5的斯格明子环、反斯格明子环以及斯格明子袋，并表征了它们的成核机制、热稳定性及塌缩路径。我们发现，高阶自旋相互作用（HOI）——它扩展了传统的双线性交换哈密顿量——对于稳定这些高$Q$自旋织构至关重要。这些环在零磁场下保持热稳定。HOI显著增强了它们的能量势垒，同时几乎不改变其尺寸，并且即使在缺乏Dzyaloshinskii-Moriya相互作用的情况下也能稳定它们。相比之下，斯格明子袋仅在存在HOI时才成核。特别是，四自旋三中心相互作用是防止高$Q$织构塌缩为铁磁态的关键因素。最后，我们识别了先前未报道的高$Q$织构的宇称依赖塌缩机制。我们的结果确立了HOI作为高$Q$成核的一个被忽视的机制。
英文摘要
Topological magnetization textures play a central role in modern magnetism. For many applications, spin textures with different topological charges $Q$ in the same system are particularly attractive. Although the coexistence of skyrmions and antiskyrmions ($|Q| = 1$) has been reported in inversion-symmetric magnets, extending this to high-$Q$ ($|Q| > 1$) textures with arbitrary charge remains elusive. Here, using an atomistic spin model parameterized from first-principles calculations, we predict the emergence of sub-20 nm high-$Q$ textures in Janus monolayers, van der Waals magnets of growing interest. We explore skyrmion and antiskyrmion rings as well as skyrmion bags with $|Q|$ up to 5, and characterize their nucleation mechanisms, thermal stability, and collapse pathways. We find that higher-order spin interactions (HOI), which extend the conventional bilinear-exchange Hamiltonian, are essential for stabilizing these high-$Q$ spin textures. The rings remain thermally stable at zero magnetic field. HOI substantially enhance their energy barriers while leaving their size nearly unchanged and stabilize them even in the absence of Dzyaloshinskii-Moriya interaction. Skyrmion bags, in contrast, nucleate only in the presence of HOI. In particular, the four-spin three-site interaction is the key ingredient preventing high-$Q$ textures from collapsing into the ferromagnetic state. Finally, we identify previously unreported parity-dependent collapse mechanisms for high-$Q$ textures. Our results establish HOI as an overlooked mechanism for high-$Q$ nucleation.
发表机构
- Zhejiang Sci-Tech University（浙江理工大学）
机构由 AI 辅助整理，请以论文原文为准。
