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arXiv 1502.05065cond-mat.mes-hall
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寻找磁跃迁机制和激活能的方法,应用于Skyrmion和反涡旋湮灭

Method for finding mechanism and activation energy of magnetic transitions, applied to skyrmion and antivortex annihilation

Pavel F. Bessarab, Valery M. Uzdin, Hannes Jónsson

摘要:

本文提出了一种寻找磁系统跃迁最小能量路径的方法,并用于确定纳米系统中Skyrmion和反涡旋湮没的机制和估计激活能。该路径相对于磁矢量的取向进行优化,而它们的幅度是固定的或从单独的计算获得。通过以下方式考虑配置空间的曲率:(1)使用测地线来评估优化期间系统的距离和位移,以及(2)将路径切线和磁力投影到由磁矢量的所有可能取向限定的流形的切线空间上。该方法,命名为测地线轻推弹性带(GNEB),并说明其实施与复杂的跃迁,包括湮灭和创建的skyrmion和antivortex状态的计算。后者的寿命内确定谐波过渡态理论使用的Alexander-Anderson模型的非共线扩展。

英文摘要:

A method for finding minimum energy paths of transitions in magnetic systems is presented and used to determine the mechanism and estimate the activation energy of skyrmion and antivortex annihiliation in nano-systems. The path is optimized with respect to orientation of the magnetic vectors while their magnitudes are fixed or obtained from separate calculations. The curvature of the configuration space is taken into account by: (1) using geodesics to evaluate distances and displacements of the system during the optimization, and (2) projecting the path tangent and the magnetic force on the tangent space of the manifold defined by all possible orientations of the magnetic vectors. The method, named geodesic nudged elastic band (GNEB), and its implementation are illustrated with calculations of complex transitions involving annihilation and creation of skyrmion and antivortex states. The lifetime of the latter was determined within harmonic transition state theory using a noncollinear extension of the Alexander-Anderson model.

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