论文标题
在驱动的手性磁铁中的Skyrmion水母
Skyrmion Jellyfish in Driven Chiral Magnets
论文作者
论文摘要
手性磁铁可以容纳称为Skyrmions的拓扑颗粒，后者带有精确的量化拓扑费$ Q = -1 $。在存在振荡磁场$ {\ bf b} _1（t）$的情况下，嵌入在铁电磁背景中的单个skyrmion将以恒定的速度$ {\ bf v} _ {\ text {trand}} $开始移动。这种运动背后的机制类似于水母在水中游泳时使用的机制。我们表明，天空的运动是一种通用现象，是在任何具有翻译模式的磁系统中产生的。通过将运动方程式投影到Skyrmion的翻译模式上，并以$ {\ bf b} _1（t）$进行二次顺序，我们获得了$ {\ bf v} _ {\ bf v} _ {\ text {trans}} $的分析表达式作为系统线性响应的功能。线性响应以及$ {\ bf v} _ {\ text {trans}} $受到天空的内部模式和散射状态以及铁磁背景的Kittel模式的影响。 $ {\ bf v} _ {\ text {trans}} $的方向和速度可以通过更改驱动场的极化，频率和相位来控制。对于具有小吉尔伯特阻尼参数$α$的系统，我们确定了Skyrmion使用的两种不同的物理机制进行移动。在较低的驾驶频率下，Skyrmion的运动是由摩擦驱动的，$ v _ {\ text {trans}} \simα$，而在高于铁磁差距的较高频率下，巨大的Skyrmion Movies by Magnon排放和$ V _ {\ trans} $ a {\ trans} $独立于$ v _ {\ trans} $。
Chiral magnets can host topological particles known as skyrmions, which carry an exactly quantised topological charge $Q=-1$. In the presence of an oscillating magnetic field ${\bf B}_1(t)$, a single skyrmion embedded in a ferromagnetic background will start to move with constant velocity ${\bf v}_{\text{trans}}$. The mechanism behind this motion is similar to the one used by a jellyfish when it swims through water. We show that the skyrmion's motion is a universal phenomenon, arising in any magnetic system with translational modes. By projecting the equation of motion onto the skyrmion's translational modes and going to quadratic order in ${\bf B}_1(t)$, we obtain an analytical expression for ${\bf v}_{\text{trans}}$ as a function of the system's linear response. The linear response and consequently ${\bf v}_{\text{trans}}$ are influenced by the skyrmion's internal modes and scattering states, as well as by the ferromagnetic background's Kittel mode. The direction and speed of ${\bf v}_{\text{trans}}$ can be controlled by changing the polarisation, frequency and phase of the driving field ${\bf B}_1(t)$. For systems with small Gilbert damping parameter $α$, we identify two distinct physical mechanisms used by the skyrmion to move. At low driving frequencies, the skyrmion's motion is driven by friction, and $v_{\text{trans}}\simα$, whereas at higher frequencies above the ferromagnetic gap, the skyrmion moves by magnon emission, and $v_{\text{trans}}$ becomes independent of $α$.
