论文标题
光学磁化逆转的现象学理论
A phenomenological theory of the optical magnetization reversal
论文作者
论文摘要
飞秒圆极化激光脉冲在磁性纳米结构中磁化的全光切换已在几种系统中证明。我们提出了一个Landau-lifshitz-Lambda（LLL）模型，该模型使用三个密度态描述了磁化动力学：两个铁磁地面状态和一个激发的光学状态。铁磁基态之一通过圆形极化的光在旋转反向状态下光学地激发，然后将其“库仑倒在”到磁化强度反向基态。光激发态的时间演变由Lindblad Master方程式描述，其中通过哈密顿式引入光学激发。耗散术语是通过Lindblad操作员引入的。 LLL模型结合了Landau-Lifshitz理论所描述的磁化的前进运动，以及三级Lambda系统的响应。光激发持续在激光脉冲的持续时间内持续，并且由于电子 - 电子相互作用而以快速速度放松。我们研究了磁化的光学方程式的特征值问题的解决方案，并确定一个连贯且不连贯的方案，并得出了可以与现有的微磁代码集成的LLL模型，以描述磁性材料的光激发。
All-optical switching of the magnetization in magnetic nanostructures by femtosecond circularly polarized laser pulses has been demonstrated in several systems. We present a Landau-Lifshitz-Lambda (LLL) model which describes the magnetization dynamics using three density states: two ferromagnetic grounds states and an excited optical state. One of the ferromagnetic ground states is optically excited by circularly polarized light to a spin reversed state, which is then "Coulomb collapsed" to the magnetization reversed ground state. The time evolution of the optically excited states is described by a Lindblad master equation, in which the optical excitation is introduced via the Hamiltonian. Dissipation terms are introduced via Lindblad operators. The LLL model combines the precessional motion of the magnetization described by the Landau-Lifshitz theory, with the response of the three level Lambda system. The optical excitation lasts for the duration of the laser pulse and the system relaxes at a fast rate due to the electron-electron interaction. We study the solution of the eigenvalues problem of the optical equation of motion for the magnetization and identify a coherent and incoherent regimes and derive an LLL model that can be integrated with existing micromagnetic codes to describe optical excitation of magnetic materials.
