Heo Changhoon, Kiselev Nikolai S, Nandy Ashis Kumar, Blügel Stefan, Rasing Theo
Radboud University, Institute for Molecules and Materials, Heyendaalseweg 135, 6525 AJ, Nijmegen, The Netherlands.
Peter Grünberg Institute and Institute for Advanced Simulation, Forschungszentrum Jülich and JARA, D-52425 Jülich, Germany.
Sci Rep. 2016 Jun 8;6:27146. doi: 10.1038/srep27146.
Magnetic chiral skyrmions are vortex like spin structures that appear as stable or meta-stable states in magnetic materials due to the interplay between the symmetric and antisymmetric exchange interactions, applied magnetic field and/or uniaxial anisotropy. Their small size and internal stability make them prospective objects for data storage but for this, the controlled switching between skyrmion states of opposite polarity and topological charge is essential. Here we present a study of magnetic skyrmion switching by an applied magnetic field pulse based on a discrete model of classical spins and atomistic spin dynamics. We found a finite range of coupling parameters corresponding to the coexistence of two degenerate isolated skyrmions characterized by mutually inverted spin structures with opposite polarity and topological charge. We demonstrate how for a wide range of material parameters a short inclined magnetic field pulse can initiate the reliable switching between these states at GHz rates. Detailed analysis of the switching mechanism revealed the complex path of the system accompanied with the excitation of a chiral-achiral meron pair and the formation of an achiral skyrmion.
磁性手性斯格明子是一种类似涡旋的自旋结构，由于对称和反对称交换相互作用、外加磁场和/或单轴各向异性之间的相互作用，它在磁性材料中以稳定或亚稳态出现。它们的小尺寸和内部稳定性使其成为数据存储的潜在对象，但要实现这一点，极性和拓扑电荷相反的斯格明子态之间的可控切换至关重要。在此，我们基于经典自旋和原子自旋动力学的离散模型，给出了外加磁场脉冲作用下磁性斯格明子切换的研究。我们发现了一个有限的耦合参数范围，对应于两个简并孤立斯格明子的共存，这两个斯格明子具有相互反转的自旋结构，极性和拓扑电荷相反。我们展示了对于广泛的材料参数，一个短的倾斜磁场脉冲如何能够以吉赫兹速率在这些状态之间引发可靠的切换。对切换机制的详细分析揭示了系统的复杂路径，伴随着手性-非手性磁子对的激发和非手性斯格明子的形成。
