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Prof. Ku Wei
Brookhaven National Laboratory, Upton, USA
E-mail: weiku@bnl.gov |
Abstract: Recent theoretical studies of physical effects of impurities on electronic structure of Fe-based superconductors will be presented. With Co- and Zn- substitution of Fe, our result indicates injection of real carriers and thus invalidates recent claim of such substitution being isovalent. On the other hand, a significant shift of chemical potential is found upon disordering the Fe vacancy of K0.8Fe1.6As2 , generating an effective “doping” to the system without additional charge carriers. The seemingly absent hole carriers are actually still present in the system, but become incoherent in nature, raising new questions concerning their role in superconductivity. Finally, with isovalent substitution of Fe by Ru, an unexpected insensitivity of the low-energy carriers is found, offering a natural explanation why superconductivity and transport of this material are so resilience to large amount of disordered impurities. Similarity of the underlying mechanism to the exotic super-diffusion mechanism will be discussed.
About the Speaker: Dr. Wei Ku, condensed matter physicist, graduated from physics department, University of Tennessee in 2000. He conducted his postdoctoral research in University of California at Davis 2000-2003, and became a physicist in Brookhaven National Laboratory in 2003. He has published more than 65 papers, at least half of which are in prestigious journals like Physical Review Letter and Natural Physics. His research area includes first-principles theoretical study of electronic structure of materials and their excitation, and related computational method development. In recent years, he focused on strongly correlated materials and disorders in functional materials.
Date&Time: December 13, 2012 (Thursday), 14:00–15:00
Location: 606 Conference Room
