AG Raster - Tunnelmikroskopie



Prof. Dr. phil. Richard Berndt



35th Anniversary of Scanning Tunneling Microscopy


Reinhardt Schuhmann, editor of Physical Review Letters, recently presented a collection of articles to celebrate the 35th anniversary of scanning tunneling microscopy and the 30th anniversary of atomic force microscopy.

Among these papers is Surface-State Lifetime Measured by Scanning Tunneling Spectroscopy by Jiutao Li, Wolf-Dieter Schneider, Richard Berndt , O. R. Bryant, and S. Crampin, Phys. Rev. Lett. 81, 4464 (1998). It has been made free to read.

PhD thesis prize of the DPG Magnetism Division awarded to Manuel Gruber


During the recent meeting of the condensed matter division of the German Physical Society Dr. Manuel Gruber successfully competed for the PhD thesis prize of the magnetism division (ThyssenKrupp Electrical Steel PhD prize).

Manuel carried out his pioneering studies at the Karlsruhe Institute of Technology with Prof. Wulfhekel and the University of Strasbourg with Dr. Beaurepaire.  He explored the impact of molecules on the magnetic properties of inorganic substrates as well as the possibility to switch the magnetization of individual molecules adsorbed on surfaces.  As a postdoc with Prof. Berndt he is presently working  on related topics within SFB 677.

Making a switchable magnet from a biomolecule


A molecule is magnetic (more precisely: paramagnetic) when its number of electrons is odd or when it contains transition metal ions like iron. Sujoy Karan from the group of Prof. Berndt investigated all-trans-retinoic acid, a non-magnetic bio-molecule with an even number of electrons, on an inert gold surface and observed that, surprisingly, the molecule may be made magnetic by passing current through it. Once it is magnetic, it may be switched back to non-magnetic. This process may be repeated and does not affect neighboring molecules. 

Currently, these observations are a serious challenge to state-of-the-art theory. From a broader perspective, they suggest that it may be possible to custom-make arbitrary arrays of ultrasmall magnets on surfaces using an unforeseen class of molecules. In addition, living organisms utilize retinoic acid for signal transduction. Whether effects related to the new observation may play a role in organisms is yet unknown. 

The experimental results from Kiel and Beijing along with theory from Munich recently appeared in Physical Review Letters.