"Magnetic and Pairing Instability in Organic Superconductors"

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Date/Time:Monday, 14 Jan 2013 from 4:10 pm to 5:00 pm
Location:Physics 0005
Phone:515-294-5441
Channel:Colloquium
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Hai-Qing Lin (Beijing Computational Science Research Center)

Abstract:

In this talk, I report our recent study on the magnetic and pair binding properties in newly discovered polycyclic aromatic hydrocarbon (PAH) superconductors including alkali-metal-doped picene, coronene, phenanthrene, and dibenzopentacene. To gain a better understanding on magnetism and electron correlation in PAH, we have performed a systematic numerical investigation on the correlation effects and model the π-electrons on the carbon atoms of a single molecule by a one-orbital Hubbard model, in which the energy difference ϵ between carbon atoms with and without hydrogen bonds is taking into account. We demonstrate that the spin polarized ground state is realized for charged molecules in the physical parameter regions, which provides a reasonable explanation of local spins observed in PAHs. In alkali-metal-doped dibenzopentacene, our results show that electron correlation may produce an effective attraction between electrons for the charged molecule with one or three added electrons. We also propose a different doping pattern which may lead to higher transition temperature. Some results on the possible structure of PAH as functions of pressure and doing will be discussed.

*Professor Hai-Qing Lin received his Master degree from Department of Physics, Iowa State University in 1983 and Ph.D. in Physics from University of California, San Diego in 1987. He worked as a research associate at Brookhaven National Laboratory and Los Alamos National Laboratory 1987-1991, and as a visiting assistant professor at Department of Physics, University of Illinois at Urbana-Champaign 1991-1995. He joined Chinese University of Hong Kong as a professor in 1995 and later served as the Chair of the Physics Department until 2011. He is now the Director of Beijing Computational Science Research Center in Beijing, China.