Implementing Real Ab Initio in Out-of-Equilibrium Dynamics

随着信息化社会的迅猛发展，对高速、低能耗的电子器件的需求日益增长。自旋电子学是一种很有前途的方法，它使用自旋而不是电子的电荷作为信息载体。为了实现所要求的高速自旋操作，需要能够强烈和快速地驱动出平衡的系统。然而，到目前为止，人们对这些快速非平衡过程背后的机制知之甚少。本研究项目的目的是通过推导非平衡理论来描述真实材料中声子、电子和自旋激发之间的超快弛豫过程，从而达到一个新的认识水平。为了实现这一目标，我将把先进的从头算方法与原子和微观模拟相结合，从而开发出超越当前模型的超短时间尺度激光激发材料动力学的创新多尺度理论。我将推导一个新的模型，包括非热弛豫过程，以探索典型系统中电子和声子的超快，非平衡相互作用，如金和石墨。此外，我将研究异质结构材料对超快激光激发的响应。特别是，我想研究金属异质结构中的光诱导自旋力矩，以探索新应用的相关机制，例如金属太赫兹发射体，并探索激光激发金属/YIG双层和三层后发生的磁振子自旋电流。此外，我将开发新的模型，探索自旋动力学中电子自旋弛豫的各种微观机制，并研究自旋和轨道矩的耦合动力学。

The tremendous growth of the information-based society has strongly increased the demand for high-speed electronic devices with low energy consumption. A promising approach is spintronics, in which the spin instead of the charge of the electron is used as information carrier. To realize the required high-speed of spin operations, systems that can be driven strongly and quickly out-of-equilibrium are needed. The mechanisms underlying these fast out-of-equilibrium processes are however poorly understood so far.The aim of this research project is to achieve a new level of understanding by deriving non-equilibrium theory to describe the ultrafast relaxation processes between phonons, electrons, and spin excitations in real materials. To reach this objective I will combine advanced ab initio methods with atomistic and microscopic simulations and thereby develop innovative multiscale theories for the dynamics in laser excited materials on ultrashort time scales beyond current models.I will derive a new model including non-thermal relaxation processes to explore the ultrafast, non-equilibrium interaction of electrons and phonons in typical systems as gold and graphite. Furthermore, I will study the response to ultrafast laser excitation in heterostructure materials. In particular, I want to study light induced spin torques in metallic heterostructures to explore the relevant mechanisms for new applications, as for example metallic terahertz emitters and explore the occurring magnon spin currents after laser excitation of metal/YIG bi- and trilayers. In addition, I shall develop new models to explore the various microscopic mechanisms of electronic spin relaxation in spin dynamics as well as study the coupled dynamics of spin and orbital moments.