Magnetization dynamics of ferromagnetic rare earth metals induced by femtosecond laser excitation

飞秒激光激发铁磁稀土金属的磁化动力学

• 批准号: 5430780
• 负责人: Professor Dr. Uwe Bovensiepen
• 金额: --
• 依托单位: Arbeitsgruppe Ultraschnelle Dynamik an Grenzflächen
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 财政年份: 2004
• 资助国家: 德国
• 起止时间: 2003-12-31 至 2009-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/5430780?language=en
• 关键词: Magnetization; dynamics; ferromagnetic; rare; earth

The project aims at a fundamental understanding of ultrafast magnetization dynamics of rare earth ferromagnets (Gd, Tb, Dy) induced by femtosecond laser pulses. Time-resolved detection of second harmonic generation and two-photon-photoemission are employed as complementary experimental techniques to study the temporal evolution of the magnetic and non-magnetic optical response as well as the exchange-split electronic structure and electron distribution of heavy lanthanides. The magnetization dynamics on the Gd(0001) surface presents an ideal model system, which is governed by (a) incoherent scattering processes leading to relaxation of the photoexcited non-equilibrium electron/spin distribution and (b) coherent magnetization dynamics in the THz frequency range. Tb and Dy present promising systems as a test case for comparison. The goals of this project are: (i) Systematic study of ultrafast magnetization dynamics of heavy rare earth systems. (ii) Identification of spin-scattering mechanisms contributing to demagnetization within several 100 fs after the optical excitation and subsequent remagnetization probed in experiments as a function of temperature, excitation density and defect concentration. (iii) Detailed understanding of coherent magnetization dynamics in the THz domain including description of damping by appropriate elementary processes.

该项目旨在对飞秒激光脉冲诱导稀土铁磁体（Gd, Tb, Dy）的超快磁化动力学有一个基本的认识。利用二次谐波产生的时间分辨探测和双光子-光电发射作为补充实验技术，研究了重系镧系元素的磁性和非磁性光响应的时间演化以及交换分裂电子结构和电子分布。Gd（0001）表面的磁化动力学呈现出一个理想的模型系统，该系统由(a)导致光激发非平衡电子/自旋分布松弛的非相干散射过程和(b)太赫兹频率范围内的相干磁化动力学控制。Tb和Dy提供了有前途的系统作为比较的测试用例。本项目的目标是：(1)系统地研究重稀土体系的超快磁化动力学。（ii）在实验中探索了光激发后100 fs内退磁和随后再磁化的自旋散射机制与温度、激发密度和缺陷浓度的函数关系。（iii）详细了解太赫兹域的相干磁化动力学，包括通过适当的基本过程描述阻尼。