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Young Investigators Group Dr. Samir Lounis

Functional Nanoscale Structure Probe and Simulation Laboratory (Funsilab)

big_fe_cluster_ir111Possible complex magnetic structure of a deposited nanocluster.

For the functionalization of nanostructures made of a few atoms it is necessary to understand and unravel the complexity of their physical behavior. There is hardly any method, which has shaped nanoscience and nanotechnology more profoundly than the scanning probe methods (SPM). With increasing availability of low temperature SPM, local electronic properties can be investigated with unprecedented space and energy resolution. This opens the vista to completely new applications, for instance the local investigation of inelastic excitation channels such as phonons, spin-flips and magnons probed by the tunneling current used in scanning tunneling spectroscopy. Equally, with low-temperature SPM allowing for the resolution of increasingly weaker interactions within nanostructures, the investigation of (relatively weak) spin-orbit related phenomena in magnetic nanostructures presents another example.  Thus, it becomes a dire need to complement the experimental results with theory for their analysis.

Our group is dedicated to the theoretical treatment of tunneling spectroscopy features and explores solid-state phenomena that are determined by small dimensions of nanoscale atomic structures arranged on surfaces ranging from clusters of a few atoms to larger islands with various sizes. Our central scientific goals are the theoretical understanding, the description and prediction of their structural, dynamical, electronic, magnetic, and transport properties by developing and applying quantum mechanical simulation tools based on the density-functional theory.

These nanostructures experience an open environment and are, thus, dynamically extremely responsive to external stimulations. The main dynamical degrees of freedom are vibrations and spin excitations that occur both in magnetic systems and are experimentally very difficult to discriminate. Therefore it is important to study both on the same footing. To this end, a particular focus lies on the formulation and development of a first-principles methodology for investigating inelastic scattering processes, in particular magnon and vibrational excitations. We also dedicate a large part of our activities to investigate space- and time-inversion broken scattering phenomena in magnetic nanostructures and study fermiology with nanostructures at surface vicinities.