论文标题
曲率对磁性天空特征的影响
The effect of curvature on the eigenexcitations of magnetic skyrmions
论文作者
论文摘要
理论上研究了磁性膜的几何缺陷（BUMP）固定在铁磁天空上的自旋特征模谱。通过对相应的特征值问题和有限元微型模拟的直接数值解，我们证明了曲率可以诱导具有较高方位角和径向量子数的局部模式，而平面天际量不存在，这是平面天际的（对于同一参数）。除了呼吸和旋转的曲率增加，所有模式的特征频率都会减少。由于翻译对称性的断裂，Skyrmion的零翻译模式获得了有限的频率并形成Gyromode，该频率描述了围绕平衡位置的天空均匀旋转。为了在分析上处理陀螺仪，我们开发了一种类似Thiele的集体变量方法。我们表明，曲线膜中的NéelSkyrmions经历了源自平均曲率梯度的驱动力。固定的Skyrmion的频率与平均曲率的第二个衍生物成正比。
Spectrum of spin eigenmodes localized on a ferromagnetic skyrmion pinned by a geometrical defect (bump) of magnetic films is studied theoretically. By means of direct numerical solution of the corresponding eigenvalue problem and finite element micromagnetic simulations we demonstrate, that the curvature can induce localized modes with higher azimuthal and radial quantum numbers, which are absent for planar skyrmions (for the same parameters). The eigenfrequencies of all modes, except the breathing and gyromodes decreases with increasing curvature. Due to the translational symmetry break, the zero translational mode of the skyrmion gains a finite frequency and forms the gyromode, which describes the uniform rotation of skyrmions around the equilibrium position. In order to treat the gyromotion analytically we developed a Thiele-like collective variable approach. We show that Néel skyrmions in curvilinear films experience a driving force originating from the gradient of the mean curvature. The gyrofrequency of the pinned skyrmion is proportional to the second derivative of the mean curvature at the point of equilibrium.
