Dynamics and Transport in Nanostructures
We investigate the influence of lateral nanostructuring and of coupling effects of ferromagnetic nanostructures with experimental methods and with micromagnetic simulations. Magnetism in micro- and nanostructured elements is of fundamental scientific interest, but has also the potential for applications, for example in spin electronic devices, memory applications, and in the medical sector. Our current work deals with the dynamics of ferromagnetic nanostructures. We use electrical transport measurements in the Hamburg laboratory and X-ray microscopy at synchrotron radiation sources, such as PETRA III in Hamburg, BESSY II in Berlin and ALS in Berkeley, CA, USA. With transport measurements in the time domain we have access to stochastic processes in varying potentials. We study spin waves in nanostructures in the frequency domain with broadband absorption spectroscopy using vector network analysis. Of particular interest is high frequency spin pumping that can be used to implement a so-called spin battery. We also explore the dynamics of domain walls, vortices, and magnonic crystals built of vortex oscillators. The influence of the interaction on the dynamic modes is studied spatially and temporally resolved with X-ray microscopy. In the future we want to extend the work on lattices of skyrmions.
Our goal is to measure and understand the magnetization dynamics of individual nanostructures on the subnanosecond time scale in order to pave the way for more complex interacting systems.
Our research is funded by The Hamburg Centre for Ultrafast Imaging (www.cui.uni-hamburg.de), the Research Training Group 1286 (www.physnet.uni-hamburg.de/GrK/gk_mmhhs), and the Collaborative Research Center 668 (www.nanoscience.de/sfb668).