Time resolved studies of coherent spin waves in ferro/antiferromagnetically coupled exchange bias systems

铁/反铁磁耦合交换偏置系统中相干自旋波的时间分辨研究

• 批准号: 5373553
• 负责人: Dr. Bernd Beschoten
• 金额: --
• 依托单位: II. Physikalisches Institut A - Physik der kondensierten Materie
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 财政年份: 2002
• 资助国家: 德国
• 起止时间: 2001-12-31 至 2007-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/5373553?language=en
• 关键词: Time; resolved; studies; coherent; spin

The goals of this proposal are systematic time-resolved studies of ultrafast magnetization reversal mechanisms in exchange bias systems using all optical pump-probe spectroscopy. This ultrafast optical approach implies the prospect of inducing and investigating basic magnetization switching and relaxation phenomena with the exchange coupled system impulsively driven by the absorbed photons on ultrafast time scales. In a first focus, the asymmetric magnetization reversal as was observed in Fe/FeF2 by neutron reflectometry shall be investigated in the time domain. In particular, we want to explore switching speed as well as precessional switching dynamics on the relevant magnetization reversal mechanisms, such as coherent magnetization rotation and domain wall propagation. In a second focus, the role of the antiferromagnetic spin structure on the magnetization reversal mechanisms in Co/CoO bilayers shall be studied. Here, the antiferromagnetic spin and domain structure can be controlled by intentionally introducing Co deficiencies (Co1-yO) in the volume of the antiferromagnetic layer. These deficiencies are known to cause and control exchange bias within the domain state model. Beside fundamental questions regarding the reversal mechanisms, we want to investigate whether the spin dynamics at the ferro-/antiferromagnetic interface can directly be influenced and modified by ultrafast optical pumping of spins near defects in the antiferromagnetic subsystem.

该方案的目标是利用全光泵浦-探测光谱对交换偏置系统中的超快磁化反转机制进行系统的时间分辨研究。这种超快光学方法意味着在超快时间尺度上诱导和研究由被吸收的光子脉冲驱动的交换耦合系统的基本磁化转换和弛豫现象。在第一个焦点中，用中子反射仪观察到的Fe/FeF2中的不对称磁化反转应该在时间域中进行研究。特别是，我们想要探索相关磁化反转机制的开关速度和进动开关动力学，例如相干磁化旋转和磁畴壁传播。在第二个焦点中，我们将研究反铁磁自旋结构在Co/CoO双层膜磁化反转机制中的作用。这里，可以通过故意在反铁磁层的体积中引入Co缺陷(Co1-Yo)来控制反铁磁自旋和磁畴结构。已知这些缺陷会导致和控制域态模型内的交换偏差。除了有关反转机制的基本问题外，我们还想研究反铁磁子系统中缺陷附近自旋的超快光抽运是否可以直接影响和改变铁磁/反铁磁界面处的自旋动力学。