Our research focuses on the static and dynamic properties of geometrially confined spin structures, magnetoresistance effects and spin transfer torque as well as spin current-induced magnetization dynamics. In addition to metallic materials, advanced oxidic multiferroics and novel materials, such as graphene are investigated. Furthermore in the group there are significant research activities in the areas of electronic properties of complex thin film materials (half metallic Heusler compounds, unconventional superconductors, shape memory alloys, thermoelectic materials, etc.).
Static and dynamic properties of ferromagnetic nanostructures and possible applications in devices (“Spintronics”):
The electronic and magnetic properties change radically when going from bulk materials to nanostructures with reduced dimensions (2D thin films, 1D wires and 0D dots). Rather than being dominated only by materials features, the shape starts to play a key role and allows one to geometrically engineer the properties. Fundamentally, novel physical effects emerge as lateral structure dimensions become comparable to or smaller than characteristic length scales (mean free path, exchange length, etc.). A prime example is spin-dependent scattering in thin film structures (Giant Magnetoresistance effect), for which the 2007 Nobel prize was awarded to P. Grünberg and A. Fert. On the temporal scale, we investigate spin dynamics excited by magnetic fields, spin - polarized currents and photons. In particular the latter allows us to go beyond the classical magnetization dynamics and study the interplay between the energy and angular momentum transfer between the electron and the spin system as well as the lattice on a femtosecond timescale.
Novel materials for basic research and applications:
Modern solid state physics theories aim at the prediction of electronic properties of complex materials. The well defined geometry and clean surfaces of epitaxial thin films are used for experimental studies of correlated materials such as Heusler compounds and unconventional superconductors. By in-situ photoemission spectroscopy, magnetotransport measurements and tunneling spectroscopy the electronic density of states is investigated. Using sophisticated deposition techniques oxidic materials can be deposited on a sub unit cell scale and it is therefore possible to engineer new materials that are dominated by the properties of the intrinsic interfaces. These artificial materials have no counterpart in nature and will enable new functionalities.