Prof. Dr. Claus M. Schneider
My research activities are concerned with the intricate and multifaceted interrelations between the electronic structure and the physical properties of matter. The current focus of my research lies on magnetism, magnetic phenomena, and their exploitation in nanoscience and information technology. The systems of interes t range from ultrathin films and thin film layer stacks through quantum wires and dots to clusters and molecules.
Magnetism is a many-electron phenomenon and is characterized by a complicated interplay of interactions taking place on different length, energy, and time scales. Thus, hybridization and correlation effects dominate the electronic structure of a magnetic system. Of particular interest is the influence of reduced dimensionality on the magnetism and the formation of quantum effects in nanoscale magnetic structures. The crosslinks between electronic structure and magnetism are addressed by a variety of spectroscopy and microscopy techniques exploiting the unique properties of synchrotron radiation, spin-polarized photoemission and x-ra y magnetooptics, as well as photoemission microscopy. These experiments are carried out at proprietary beamlines operated at the synchrotron radiation facilities BESSY (Berlin) and DELTA (Dortmund).
A second major research topic deals with the behavior of magnetic systems on short and ultrashort time scales. In the nano- and picosecond regime, different magnetodynamic processes such as domain nucleation, magnetization rotation and precession are studied by a joint approach, involving a variety of pump-probe techniques and micromagnetic simulations. Laser-based approaches provide a high time-resolution, whereas time-resolved photoemission microscopy combines high lateral resolution with large magnetic sensitivity and element selectivity. Spin-dynamics in the sub-picosecond regime, is governed by energy and angular momentum transfer processes taking place between the electron, spin, and lattice subsystems. Understanding these processes provides an access to fundamental spin-dependent interactions, such as spin-orbit and exchange coupling. Such experiments are performed by femtosecond pump-probe methods.
My third main topic of interest is Spintronics, i.e., the physics of spin-dependent transport processes. The current studies concentrate on the fundamental physics of spin transport and transfer phenomena. This also includes the development of new magnetic materials systems for the use as electrodes, such as, e.g., magnetic semiconductors or halfmetallic ferromagnets. A particular emphasis is puton the development of smart magnetic switching alternatives, for example, magnetic switching processes and magnetization dynamics induced by spin-polarized electrical currents. The interest in these current-induced magnetic switching phenomena is just one facet of the broader activities on Nanospintronics, which are occupied with the spin transport through nanostructures, such as magnetic point contacts or carbon nanotubes.