Energy and angular momentum exchange between electron and spin-system in ferromagnetic films

本课题研究的是铁磁固体中激发态电子与自旋系统之间的相关能量和角动量传递动力学。这些耗散过程对于超快自旋动力学领域的许多基本机制都是重要的。使用不同的激光脉冲强度，我们将能够区分两种不同的机制：1)单个激发电子与自旋系统的直接相互作用。特别强调的是自旋波损失模式的强度，局部与非局部自旋轨道耦合，以及界面动量占用的强度。2)高激发电子系统与冷自旋系统之间存在强热非平衡的情况。目的是详细了解超快加热激光脉冲后磁化的响应。研究将采用飞秒泵浦探测方法：磁光克尔效应和线性和非线性光电发射。研究将集中在具有局域自旋矩的流动铁磁体Co， Ni， Fe和铁磁体Gd的薄膜和多层上。

The subject of this project is to study the dynamics of the relevant energy and angular momentum transfer between excited electrons and the spin system of a ferromagnetic solid. These dissipation processes are important for many fundamental mechanisms in the field of ultrafast spin dynamics. Using different laser pulse intensities we will be able to distinguish two different regimes: 1) the direct interaction of a single excited electron and the spin-system. Special emphasis will be given to the strength of spin-waves loss modes, local vs. nonlocal spin-orbit coupling, and the strength of interface momentum take-up. 2) the case of a strong thermal non-equilibrium between a highly excited electron system and a cold spin system. The aim is to gain detailed insight into the response of the magnetization after an ultrafast heating laserpulse. The studies will be performed by femtosecond pump-probe methods: magneto-optic Kerr effect and linear and nonlinear photoemission. The investigations will focus on thin films and multilayers of the itinerant ferromagnets Co, Ni, Fe and of the ferromagnet Gd with a localized spin moment.