The Physics Colloquium: Philip Phillips (University of Illinois Urbana-Champaign) "Solving the Mott Problem"

The Bardeen-Cooper-Schrieffer (BCS) theory of superconductivity described all superconductors until the 1986 discovery of the high-temperature counterpart in the cuprate ceramic materials.  This discovery has challenged conventional wisdom as these materials are well known to violate the basic tenets of the  standard theory of metals in which single elecrtrons are the well-defined excitations that carry the current.  The central problem is that cuprates start off their lives as Mott insulators where the standard theory would predict metallic transport.  The natural question arises: What is the simplest model for a doped Mott insulator yields tractable results.  In this talk, I will explain the Mott problem and show that breaking an overlooked symmetry in the standard theory of metals leads to a set of exactly solvable models that can be deformed continuously into the gold standard for Mott problem.  The nature of the superconducting state will be discussed.