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     COLLOQUIUM OF THE COMPUTATIONAL MATERIALS SCIENCE CENTER
   AND THE SCHOOL OF PHYSICS, ASTRONOMY AND COMPUTATIONAL SCIENCES
                       (CSI 898-Sec 001)
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      Theory of Correlated Superconductors: s-wave versus d-wave

                           Predrag Nikolic
      School of Physics, Astronomy and Computational Sciences
                 George Mason University, Fairfax, VA

The main mystery behind high-temperature superconductivity in cuprates is the 
pseudogap state. Its properties defy all well established paradigms in 
condensed matter physics, and reveal the crucial importance of strong electron 
correlations. There are two main and opposing views of the pseudogap state: a 
yet unknown competing order, or a precursor state to superconductivity. This 
talk will present a unifying view, by demonstrating that local pairing 
fluctuations, vortex liquid dynamics and other precursor phenomena can emerge 
quite generally whenever fermionic excitations remain gapped across the 
superconducting transition, regardless of the gap origin. As a tractable 
model, we consider a lattice band insulator with short-range attractive 
interactions. We reveal and characterize a pseudogap state in this model using 
a variety of techniques, such as renormalization group and systematic 
perturbation theory. While the model has a direct realization in ultra-cold 
atomic gases near unitarity, we will focus on how its universal properties and 
phenomenology could help us understand electronic systems such as amorphous 
thin films and cuprates.

                      Monday, February 21, 2011
                               4:30 pm
                    Room 301, Research I, Fairfax Campus

Refreshments will be served at 4:15 PM.
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Find the schedule at http://cmasc.gmu.edu/seminar/schedule.html