方形晶格斯格明子晶体中均匀铁磁性与有限波矢不稳定性之间的竞争
Competition between uniform ferromagnetism and finite-wave-vector instabilities in square-lattice skyrmion crystals
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中文总结 AI 辅助
本研究通过模拟退火揭示，在中心对称自旋模型中，均匀铁磁相互作用的强弱调控方形晶格斯格明子晶体相的稳定与消失，并阐明其形成机制。
中文摘要 AI 辅助
我们研究了具有动量相关磁相互作用（包括均匀铁磁相互作用、两个正交有限波矢处的易轴各向异性相互作用、高次谐波波矢相互作用以及外磁场）的中心对称自旋模型中的方形晶格斯格明子晶体态。利用模拟退火计算，我们确定了作为磁场和均匀铁磁相互作用强度函数的低温磁相图。我们发现，当均匀铁磁相互作用较弱时，斯格明子晶体相在中间磁场下得以稳定，表现出非共面双Q自旋纹理、有限标量自旋手性以及高次谐波分量。增强均匀铁磁相互作用会通过直接一级相变抑制并最终消除斯格明子晶体相，使其转变为完全极化态，而减弱该相互作用则会扩大斯格明子稳定区域，并在高磁场下稳定单Q锥形螺旋相。这些结果阐明了中心对称磁体中方形晶格斯格明子形成的机制。
英文摘要
We investigate square-lattice skyrmion crystal states in a centrosymmetric spin model with momentum-dependent magnetic interactions, including a uniform ferromagnetic interaction, easy-axis anisotropic interactions at two orthogonal finite wave vectors, higher-harmonic wave-vector interactions, and an external magnetic field. Using simulated annealing calculations, we determine the low-temperature magnetic phase diagram as functions of magnetic field and uniform ferromagnetic interaction strength. We find that the skyrmion crystal phase is stabilized at intermediate fields when the uniform ferromagnetic interaction is weak, exhibiting a noncoplanar double-$Q$ spin texture, finite scalar spin chirality, and higher-harmonic components. Increasing the uniform ferromagnetic interaction suppresses and eventually eliminates the skyrmion crystal phase through direct first-order transitions to the fully polarized state, whereas its weakening expands the skyrmion stability region and stabilizes a single-$Q$ conical spiral phase at high fields. These results clarify the mechanisms governing the square-lattice skyrmion formation in centrosymmetric magnets.
发表机构
- Graduate School of Science, Hokkaido University（北海道大学理学研究科）
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