Theoretical Condensed Matter Physics Seminar
2 p.m., Thursday, June 21, 2001
Room 1304, Physics Building
Spin fluctuations and pseudo-gap in the 2D Hubbard model
Nicolas Dupuis
(Laboratoire de Physique des Solides, Orsay, France)
Abstract: In the strong-coupling limit, the Hubbard model
reduces to the Heisenberg model. In the low-energy limit, the latter
can be mapped onto a non-linear sigma model (NLSM). We show that
spin fluctuations in the Hubbard model can be described by a NLSM both
in the weak and strong-coupling regimes. Solving the NLSM within
a "large N" approximation, we show that the system is always disordered
at finite temperature with an exponentially large magnetic correlation
length at low temperature (renormalized classical regime). Finally,
in the weak-coupling regime, we discuss the absence of quasi-particles
and the existence of a pseudo-gap within a one-loop approximation.
Our results are compared to other (weak-coupling) approaches such as FLEX
or the two-particle self-consistent theory.
Host: Victor Yakovenko
Back to the Condensed Matter Physics Seminar
Home Page