On Thursday, March 18th 2004, at 12:30 PM in Room SCI 352 we will have a
especial condensed matter seminar delivered by Prof. Andrey Chubukov from
University of Wisconsin. Prof. Chubukov is visiting the Physics Department
under the QCMT visitor's program. |
"Self-generated locality near quantum-critical points".
A. Chubukov - University of Wisconsin
I discuss recent results obtained for a set of fermionic systems near commensurate and incommensurate spin and charge density wave ordering. I consider situations when a system is a weakly coupled Fermi liquid far from a quantum critical point, but Fermi-liquid behavior is destroyed at criticality by low-energy fluctuations. I argue that, in this situation, fermionic self-energy, resulting from the exchange of near-gapless bosonic modes, becomes local in the strong coupling limit, in the sense that its frequency dependence is much stronger than its momentum dependence. I show how this behavior is related to Landau theory of a Fermi liquid, and argue that the locality of the self-energy invalidates the idea of a precursor instability in a Fermi liquid,known as a "fermionic condensate".