论文标题
由于电子 - 电子散射及其与铁磁体中动量松弛的关系，超快消灭动力学
Ultrafast Demagnetization Dynamics Due to Electron-Electron Scattering and Its Relation to Momentum Relaxation in Ferromagnets
论文作者
论文摘要
我们从理论上分析了由于自旋轨道耦合和电子电子库仑散射的相互作用，因此在铁磁模型系统中分析了灭绝动力学。我们计算$ K $分辨的电子还原旋转密度矩阵，包括内部自旋轨道和交换场周围的进型动力学以及用于密度和旋转相干的电子库仑散射。基于与完整Boltzmann散射积分的数值溶液的比较，我们确定$ k $分辨的还原性旋转密度矩阵动力学使用更简单的普遍放松时间ANSATZ来很好地描述了降低的旋转密度矩阵。这个Ansatz允许人们将电磁动力学基础的复杂散射动力与物理有意义的动量放松时间$τ$联系起来。我们的方法重现了反电效应时间$τ_{m} \ propto 1/τ$和$τ_{m} \ proptoτ$的行为，分别为短和长$τ$的限制，并且也对中间方案有效。因此，ANSATZ提供了一种工具，可以在处理磁化动力学（例如传输或磁子/声子动力学）的其他贡献的方法中包含正确的消灭行为。
We analyze theoretically the demagnetization dynamics in a ferromagnetic model system due to the interplay of spin-orbit coupling and electron-electron Coulomb scattering. We compute the $k$-resolved electronic reduced spin-density matrix including precessional dynamics around internal spin-orbit and exchange fields as well as the electron-electron Coulomb scattering for densities and spin coherences. Based on a comparison with numerical solutions of the full Boltzmann scattering integrals, we establish that the $k$-resolved reduced spin-density matrix dynamics are well described using a simpler generalized relaxation-time ansatz for the reduced spin-density matrix. This ansatz allows one to relate the complicated scattering dynamics underlying the demagnetization dynamics to a physically meaningful momentum relaxation time $τ$. Our approach reproduces the behaviors of the demagnetization time $τ_{m} \propto 1/τ$ and $τ_{m} \propto τ$ for the limits of short and long $τ$, respectively, and is also valid for the intermediate regime. The ansatz thus provides a tool to include the correct demagnetization behavior in approaches that treat other contributions to the magnetization dynamics such as transport or magnon/phonon dynamics.
