Improved ab initio prediction of EPR parameters - unambiguous identification of paramagnetic structures in materials science

• Antragsteller: Dr. Uwe Gerstmann
• Fachliche Zuordnung: Theoretische Physik der kondensierten Materie
• Förderung: Förderung von 2005 bis 2008
• Projektkennung: Deutsche Forschungsgemeinschaft (DFG) - Projektnummer 20069000

• Erstellungsjahr: 2008

Zusammenfassung der Projektergebnisse

Besides a higher numerical accuracy, the SO-including method has the advantage of higher flexibility: In the remaining weeks of my stay at the IMPMC in Paris, we are planing to implement a possibility to predict the x-ray magnetic circular dichroism (XMCD) cross section, given by the diffenrence of the x-ray absorption with respect to left and right circular polarised light σXMCD = σ(e) − σ(e∗). Due to strong similarities between the g-tensor and the XMCD cross section (both are completely vanishing if the spin-orbit coupling is left out) the combination of the existing approach of calculating the cross section of x-ray absorption and the self-consisting treatment of the spin-orbit coupling is very promising. We are confident that a similar approach will be possible for the SO-part of the zero-field splitting (ZFS) of systems with more than one unpaired electron, e.g. excited triplet states in biophysical systems. The ZFS parameters of a special structure rarely coincide with those of another, they depend strongly from the environment and from details of the geometry. They can, thus, serve as an additional efficient analytical tool if properly analyzed. All this shows that forced by the limitations of the perturbative GI-PAW approach the change of the time schedule results at the end in a more flexible program package with an exceptionally high potential for interesting extensions that should be realised in the next future. In tight collaboration between theory and experiment, as already realised during my stay at IMPMC in Paris, our flexible concept will lead to more reliable interpretation of a wide range of spectroscopic data and, thus, to further progress in various fields of modern materials science.

Projektbezogene Publikationen (Auswahl)

• ”Phosphorus Donors in Highly Strained Silicon ”, Phys. Rev. Lett. 97, 166402, 1 – 4, 2006
  H. Huebl, A.R. Stegner, M. Stutzmann, M.S. Brandt, G. Vogg, F. Bensch, E. Rauls, and U. Gerstmann
  
• ”New Insight in Scandium-mediated Growth Techniques: Sc-related Defects in 4H-SiC and 6H-SiC ”, Mat. Sci. Forum 556-557, 469 – 472, 2007
  U. Gerstmann, S. Greulich-Weber, E. Rauls, J.-M. Spaeth, E.N. Kalabukhova, E.N. Mokhov, and F. Mauri
  
• ”Nitrogen Donor Aggregation in 4H-SiC: g-Tensor Calculations ”, Mat. Sci. Forum 556-557, 391 – 394, 2007
  U. Gerstmann, E. Rauls, S. Greulich-Weber, E.N. Kalabukhova, D.V. Savchenko, A. Pöppl, and F. Mauri
  
• ”Ga self-interstitials in GaN investigated by ab initio calculations of the electronic g-tensor ”, phys. stat. solidi (b) 245, 924 – 926, 2008
  U. Gerstmann, A.P. Seitsonen, and F. Mauri