P. Vilmercati et al., Phys. Rev. B 79 , 220503(R) (2009)

1. Three-Dimensional Layered Fe-based SuperconductorsNorman Mannella, University of Tennessee Knoxville, DMR 0804902 We have investigated the electronic structure of iron-based high temperature superconductors (Fe-SC) using Angle Resolved Photoemission Spectroscopy (ARPES) and other soft x-ray spectroscopies. Our results reveal that the description of the electronic structure are not strongly modified by the occurrence of electron correlations. These findings suggest that the underlying physics and the origin of superconductivity in these materials are likely to be quite different from those of the cuprate high-temperature superconductors. These new superconductors cannot easily be categorized with previously studied materials, and should be considered a class of their own. Our latest results (unpublished) reveal the importance of magnetic correlation via direct measurement of a magnetic moment on the Fe site fluctuating at very fast time scales. This work explains and resolves the apparent dichotomy between localized and itinerant descriptions of magnetism in Fe-SC and more generally system hosting itinerant magnetism. P. Vilmercati et al., Phys. Rev. B 79, 220503(R) (2009) C. Parks Cheney et al., Phys. Rev. B 81, 104518 (2010) F. Bondino et al, Phys. Rev. B 82, 014529 2010

2. Strongly Correlated Electron Systems Norman Mannella, University of Tennessee Knoxville, DMR 0804902 Our lab provides a stimulating environment for the intellectual growth of students and postdocs. Students learn a multitude of skills ranging from optics to vacuum technology in the same laboratory. Farragut High School students are also exposed to basic principles of modern technologies by performing electron spectroscopy experiments. Students and postdocs are educated in a collaborative atmosphere that includes scientists from Oak Ridge National Lab, (ORNL), Argonne National Lab (ANL), Lawrence Berkeley Lab (LBL), and international universities. An undergraduate student optimizes the laser power for time-resolved experiments.