|March 12, 2014
Bldg. 440, A105-106
"Supra-molecular Architectures at Surfaces for Probing Structure, Electron and Spin States," by Thomas A. Jung, Paul Scherrer Institute, hosted by Saw Wai Hla
Abstract: Well-defined electronic and spintronic interfaces can be architected by combining self-assembly and surface science. The atomically clean metal surface in ultrahigh vacuum provides a very specific environment affecting the behavior of the ad-molecules as well as the adsorbent-adsorbate interaction. Depending on the bonding at the interface, complex electronic and magnetic interaction can occur that can be explored by using spectromicroscopy correlation, in this case, photoemission and photoabsorption spectroscopy and scanning tunnelling microscopy.
One example is provided by the emergence of quantum dot states from the interaction of a porous network with the two-dimensional (Shockley) surface state of Cu(111), which exhibit sufficient residual coupling to show the emergence of a band-like structure in angle-resolved photoemission experiments. In another example, specifically chosen surface supported molecules have been shown to exhibit ferromagnetic or antiferromagnetic exchange interaction, and their spin system has shown change induced by physical parameters and/or chemical stimuli. By combining supramolecular chemistry with on-surface coordination chemistry, the reversible spin switching of self-assembled bimolecular arrays has recently been demonstrated.
These examples all have in common that the molecular interfaces are well defined by their production from atomically clean substrates and molecular building blocks. The physics and chemistry of these unprecedented systems, which are addressable by scanning probes, provide insight into novel materials in their assembly and their electronic and spintronic properties, which emerge from the interaction of their components down to the scale of single atoms, molecules, and bonds.