Magnetization dynamics on pico- and femtosecond timescales is an extremely hot scientific topic, that can open doors for future advanced electronics applications based on electron spin control. In our experiments, we explore non-equilibrium spin dynamics in ferromagnetic materials on femtosecond time scales.
To study the the spin dynamics at these extreme time scales, we take advantage of our state-of-art pump-probe experimental techniques using visible- and soft X-ray light generated by either femtosecond pulsed lasers or synchrotron sources.
Recent developments in laser-generated higher harmonics provide new cutting edge extension of our experimental capabilities. By merging the properties of ultrafast lasers and a synchrotron in a single experiment, we can combine femtosecond temporal resolution with elemental, chemical and structural selectivity, thus gaining additional insight into the physics governing spin dynamics in novel ferromagnetic materials, alloys and multilayers.
The scientific activities of the laser group are outlined below.
The particular properties of magnetic micro- and nanostructures result from of a complicated interplay between several energy terms. A detailed description of the magnetic structure is a prerequisite for the understanding of magnetization processes in magnetic particles. The theory of micromagnetism provides the mathematical framework to describe static and magnetization structures. Usually, a solution of the underlying equations can only be achieved with numerical methods. Micromagnetic simulations can provide precise information on the spatio-temporal evolution of the magnetization in sub-micron sized ferromagnetic particles. A custom-developed micromagnetic finite-element code, called TetraMAG, is used to model the static and the dynamic magnetization.
In many cases, the simulations are in direct connection with an experimental investigation, which allows for a direct comparison of measured and computed data. This combination of experiment and simulation is particularly powerful to establish a well-founded understanding of fundamental magnetization processes in mesoscopic ferromagnets. Our current research projects in micromagnetic modelling include, e.g., the study of propagating spin waves in thin films, strips and rings; current-induced magnetization dynamics; resonant modes in patterned elements and three-dimensional magnetic structures in mesoscopic particles.