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Query: faculty: "FNWI" and publication year: "2010"

AuthorJ.S.M. Klei
TitleLow-Energy-Electron- Diffraction on Pnictide Superconductors : Probing the surface of BaFe2−xCoxAs2 and Fe1+δSe1−yTey
SupervisorM.S. Golden
Year2010
Pages60
FacultyFaculty of Science
Institute/dept.FNWI: Van der Waals-Zeeman Instituut
ProgrammeFNWI MSc Physics
AbstractIn this thesis energy-dependent low-energy electron diffraction measurements are described, that were carried out on BaFe2−xCoxAs2 and FeSe1−yTey single crystals, two recently discovered pnictide superconductors. This was done in order to investigate the structure of the cleavage surface of BaFe2−xCoxAs2, which is still under debate. To be able to perform the energy-dependent measurements properly, a lot of effort went into the development of the experiment. This is because I(V)-LEED experiments had never been done in this research group before. The developed experimental procedures, as well as the first resulting I(V)-curves, are described. Furthermore, significant time is spent on discussing the possible scenarios for the cleavage surface of BaFe2−xCoxAs2, both from qualitative arguments as well as based on structural refinements based on the simulation of the I(V)-LEED data performed by a collaborating group. From the results it is concluded that the cleavage surface of BaFe2−xCoxAs2 most likely contains a reconstructed half layer of barium atoms and that the atomic
positions in the underlying iron and arsenic layers are also changed compared to the bulk of the crystal. The difference between the bulk and the surface of these samples should be carefully taken into consideration in the future when dealing with surface sensitive measurements on this topical family of high temperature
superconductors.
Document type scriptie master
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