In this combined experimental and theoretical work, we report on the evolution of the skyrmion radius and its destruction in the system Co/Ru(0001) when an out-of-plane magnetic field is applied. At low fields, skyrmions are metastable and display an elliptical instability in which along the short axis, the spin texture approaches that of the spin-spiral phase and the long axis expands in order to go back to the spin-spiral ground state. At high fields, we observe round skyrmions of finite size up to the collapse field Bc, where they are destroyed and the topological charge is annihilated. We estimate Bc via numerical methods based on magnetization dynamics simulations parametrized by density functional theory calculations and compare it to experimental scanning tunneling microscopy observations obtained at ≈ 30 mK.

中文翻译：

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斯格明子在磁场中的不稳定性

在这项结合实验和理论的工作中，我们报告了当施加面外磁场时斯格明子半径的演变及其在 Co/Ru(0001) 系统中的破坏。在低场下，斯格明子是亚稳态的并表现出椭圆不稳定性，其中沿短轴，自旋纹理接近自旋 - 螺旋相，长轴扩展以返回自旋 - 螺旋基态。在高场，我们观察到有限大小的圆形斯格明子直到坍缩场 Bc，在那里它们被破坏，拓扑电荷被消灭。我们通过基于密度泛函理论计算参数化的磁化动力学模拟的数值方法估计 Bc，并将其与在 ≈ 30 mK 下获得的实验扫描隧道显微镜观察结果进行比较。