周期性障碍阵列上的斯格明子动力学与拓扑分选
Skyrmion Dynamics and Topological Sorting on Periodic Obstacle Arrays
AI总结：
本文研究直流驱动下斯格明子在方形障碍阵列上的动力学，发现霍尔角呈量子化台阶变化，并在多物种集体区域实现拓扑分选，类比胶体粒子分选方法。
摘要：
我们研究了在直流驱动下，斯格明子与方形障碍阵列相互作用时，障碍尺寸和阻尼变化对其行为的影响。当沿固定方向施加驱动时，我们发现斯格明子最初沿驱动方向运动，但由于马格努斯力的作用，也会产生横向于驱动方向的位移。斯格明子霍尔角（表示斯格明子运动方向与驱动方向之间的差异）随着驱动的增加而呈一系列量子化台阶式增大，这是斯格明子运动锁定到障碍阵列的特定对称方向的结果。在这些台阶上，斯格明子与整数个障碍发生碰撞，从而产生周期性运动。不同锁定台阶之间的转变与速度-力曲线中的跳跃或凹陷相关。在某些区域，斯格明子霍尔角实际上高于无障碍时出现的固有斯格明子霍尔角。在零阻尼极限下，斯格明子霍尔角为90°，我们发现随着阻尼增加，该角度减小。对于集体区域中多个相互作用的斯格明子种类，我们发现低驱动下会出现堵塞行为，此时不同斯格明子种类强耦合并沿相同方向运动。随着驱动增加，种类解耦，每种可锁定到障碍晶格的不同对称方向，从而能够进行拓扑分选，类似于用于分选在二维障碍阵列上移动的不同胶体粒子种类的粒子分选方法。
英文摘要：
We examine skyrmions under a dc drive interacting with a square array of obstacles for varied obstacle size and damping. When the drive is applied in a fixed direction, we find that the skyrmions are initially guided in the drive direction but also move transverse to the drive due to the Magnus force. The skyrmion Hall angle, which indicates the difference between the skyrmion direction of motion and the drive direction, increases with drive in a series of quantized steps as a result of the locking of the skyrmion motion to specific symmetry directions of the obstacle array. On these steps, the skyrmions collide with an integer number of obstacles to create a periodic motion. The transitions between the different locking steps are associated with jumps or dips in the velocity-force curves. In some regimes, the skyrmion Hall angle is actually higher than the intrinsic skyrmion Hall angle that would appear in the absence of obstacles. In the limit of zero damping, the skyrmion Hall angle is 90$^\circ$, and we find that it decreases as the damping increases. For multiple interacting skyrmion species in the collective regime, we find jammed behavior at low drives where the different skyrmion species are strongly coupled and move in the same direction. As the drive increases, the species decouple and each can lock to a different symmetry direction of the obstacle lattice, making it possible to perform topological sorting in analogy to the particle sorting methods used to fractionate different species of colloidal particles moving over two-dimensional obstacle arrays.
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