Electronic theory of ultrafast spin dynamics

磁性介质中存储密度和读/写速度的极大提高正在达到其物理极限。实际的读写过程发生在纳秒量级。新开发的方法，如进动开关，已经显示出达到100皮秒的时间尺度的潜力，而与之竞争的非磁光技术已经展示了更快的开关。因此，对磁动力学加速的需求迫在眉睫。因此，这个项目的目标是从理论上探索和理解亚皮秒时间尺度上自旋动力学的物理过程、可能性和局限性。该项目将专注于磁开关全光技术的理论探索，这种技术保证了设备操作的非接触模式，利用了超快时间尺度上磁动力学的相对论和量子性质。本论文将以铁磁性金属、反铁磁性过渡金属氧化物和磁性小纳米颗粒作为理论研究的原型材料。这些材料的量子力学描述的电子理论将基于第一性原理和参数方法，以便能够同时解释材料科学和超快自旋动力学的磁光方面。

The tremendous increase in storage density and read/write speed in magnetic media is reaching its physical limits. Actual read-write processes take place in the order of nanoseconds. Newly developed methods, like precessional switching, have shown the potential to reach time scales of a hundred picoseconds, while competing non-magnetic optical technologies have already demonstrated even faster switching. Therefore, the need for an upspeed of magnetic dynamics is imminent. Thus it is the goal of this project to theoretically explore and understand the physical processes, possibilities, and limitations of spin dynamics on the subpicosecond time scale. The project will be focussed on the theoretical exploration of all-optical technologies of magnetic switching, which guarantee a contact-free mode of device operation, exploiting the relativistic and quantum nature of magnetic dynamics on ultrafast time scales. Ferromagnetic metals, antiferromagnetic transition metal oxides, and small magnetic nanoparticles will be taken as prototypical materials for this theoretical investigation. The electronic theory for the quantum mechanical description of these materials will be based on both first principles and parametrized approaches in order to be able to account for the materials science and the magneto-optical aspects of ultrafast spin dynamics simultaneously.