Depondt Ph, Mertens F G
Institut des NanoSciences de Paris, UMR CNRS 7588, Université Pierre et Marie Curie-Paris 6, F-75252 Paris Cedex 05, France.
J Phys Condens Matter. 2009 Aug 19;21(33):336005. doi: 10.1088/0953-8984/21/33/336005. Epub 2009 Jul 27.
Spin dynamics with the Landau-Lifshitz equation has provided topics for a wealth of research endeavors. We introduce here a numerical integration method which explicitly uses the precession motion of a spin about the local field, thus intrinsically conserving spin lengths, and therefore allowing for relatively quick results for a large number of situations with varying temperatures and couplings. This method is applied to the effect of long-range dipole-dipole interactions in two-dimensional clusters of spins with nearest-neighbor XY-Heisenberg exchange interactions on a square lattice at finite temperature. The structures thus obtained are analyzed through orientational correlations functions. Magnon dispersion curves, different from those of the standard Heisenberg model, are obtained and discussed. The number of vortices in the system is discussed as a function of temperature and typical examples of vortex dynamics are shown.
基于朗道-里夫希茨方程的自旋动力学为大量研究工作提供了主题。我们在此介绍一种数值积分方法，该方法明确利用自旋绕局部场的进动运动，从而本质上保持自旋长度，因此对于大量具有不同温度和耦合的情况能够得到相对快速的结果。此方法应用于有限温度下，具有最近邻XY-海森堡交换相互作用的二维自旋簇中长程偶极-偶极相互作用的效应。通过取向关联函数对由此获得的结构进行分析。得到并讨论了与标准海森堡模型不同的磁振子色散曲线。讨论了系统中涡旋的数量随温度的变化，并展示了涡旋动力学的典型例子。
