2012 - Mohammad Rashidi
Investigation of the Kondo Effect in an Organic Radical by Scanning Tunneling Microscopy and Spectroscopy
Research stay at the Physics and Astronomy Department, Ohio University, Ohio, USA
17.02.2012 - 27.02.2012 and 02.03.2012 - 10.03.2012
I am a PhD student under the supervision of Prof. Reinhold Koch at the Department of Solid State Physics. My research focus is to investigate the structural, magnetic and electronic properties of organic molecules on metal and semiconductor surfaces down to the atomic scale by employing low temperature scanning tunneling microscopy (LT-STM) spectroscopy. LT-STM is an extremely powerful state of the art technique that places severe demands on researchers to master the technical challenges of performing the experiments and analyzing the results. To improve on our technical skills, I had a short visit at the renowned LT-STM group of Prof. Saw-Wai Hla at Physics and Astronomy Department, Ohio University, Ohio, USA. It is one of the most highly recognized groups in this field. The visit was scheduled for two weeks and accompanied by my participation in the American Physical Society (APS) March Meeting in Boston (one extra week). Besides acquiring expertise on specific experimental challenges (Kondo spectroscopy) and data analysis (2nd order spectra), I had the opportunity to discuss our recent results with Prof. Hla and his group members. I presented our results achieved at our department in Linz as a talk in the group. Recently, in our group in Linz we have investigated an all-organic free radical on Au(111) surface and found the characteristic Kondo behavior. The Kondo effect arises due to the screening of the localized magnetic moment by the conduction electrons of the host metal. This screening increases the scattering cross-section of the conducting electrons due to spin-flip exchange interaction increasing the resistance of the system bellow the characteristic Kondo temperature. This conductance change can be measured by tunneling spectroscopy at the single-atom scale . The discussion with Prof. Hla and his group members and getting their feedback was very helpful for interpreting our data. Our results were presented as a talk at the APS March meeting entitled “Evidence of Kondo effect in organic radical nanoassemblies”. My visit forms an important part of my PhD work in Linz and was a unique opportunity to develop my knowledge on scanning tunneling microscopy and spectroscopy techniques.
 V. Madhavan, W. Chen, T. Jamneala, M. F. Crommie, and N. S.Wingreen, Science 280:567, (1998).