programs of the Lorentz center are supported financially by NWO and FOM.
funding for this workshop from the Lorentz Fund is gratefully
description of the workshop
Correlated Electron Systems''
Sasha Balatsky, Los Alamos, NM, USA
Zaanen, Leiden University, Netherlands
The aim of
this workshop is to bring together a relatively small group of theorists and
experimentalists to work in an informal setting at the frontier of the
physics of strongly correlated electron systems.
This field of science is at present in a rapid flux
and our explicit goal is to bring together the developments in the various
subareas of this general field. Cuprate high Tc superconductivity will play a central role, given
the revolutionary developments taking place at the moment both with regard to
the evidences for meso-scale self-organizations (stripes), as with regard to
the physics of the superconducting state itself (nodal fermions, resonance
A next subject is the
colossal magneto-resistance manganites, with its astonishing variety of
electronic ordering phenomena, while on the most basic level the questions are
quite similar as in the context of the cuprates. Is the low temperature
metallic state of the manganites a band-structure affair, or do the intricate
meso-scale correlations, seen at high temperature, persist in some quantum-mechanical form?
newcomers are the ruthenates, where it
now seems established that p-wave or f-wave superconductors are
realized. Is it so that this superconductivity is driven by spin-fluctuations
while the normal state is a Fermi-liquid, or are there stronger similarities
with the mysterious physics of cuprates?
The recent experiments by Batlogg and coworkers involving C60
and pentacene have revived the interest in the organic metals and
superconductors, suggesting that the established views on the nature of these
electron systems might well be flawed.
The superconducting Tc's are too high to be explained with BCS while also
doping dependences etcetera do not make sense when viewed from a conventional
These findings give new impetus to the idea that the superconductivity has to do with that of
The latest addition to this list might be MgB2,
which was very recently found to be
also a high Tc superconductor with its 39 K transition
temperature. Does this material share other characteristics with
the established unconventional superconductors?
We hope that when the workshop takes place, enough information is
available to answer this question.
Alltogether, there are reasons to believe that the unconventional and
mysterious electronic properties in all these systems are related to a common
denominator, to yet to be discovered new principles active in these strongly
interacting quantum systems.
workshop is intended to be a forum for that part of the community which is
sharing this hypothesis.