Seminários

Event

Title:: Seminário de Matéria Condensada - David M. Edwards
When:: 14.03.2014 11.00 h
Where:: Auditório 201 - Niterói
Category:: Seminários

Description

Data: Sexta-feira, 14/03/2014

Horário: 11:00

Local: Sala 201

O Professor David Edwards, do Imperial College da Universidade de
Londres, visitará o IF-UFF na próxima sexta-feira, dia 14/03/2014. Às
11:00 ele ministrará, na sala 201, o seminário entitulado "Fifty years
of the Hubbard model, from magnetism and metal-insulator transitions
to superconductivity and cold atoms". O seminário é voltado para
não-especialistas. O Professor Edwards foi um dos protagonistas no
desenvolvimento da teoria do magnetismo no século XX, e continua dando
contribuições extremamente relevantes à área. Abaixo encontra-se um
resumo do seminário.

In 1963 John Hubbard published a novel treatment of a model for
fermions in a narrow energy band with strong short-range interactions.
It was originally aimed at understanding ferromagnetism in transition
metals but its most striking result was a crude description of the
metal-insulator (Mott) transition which occurs in systems such as
transition metal oxides. In 1964 Hubbard gave a better theory of this
transition with an improved solution of his model in which he invented
a many-body coherent potential approximation (CPA). The one-electron
CPA, later used extensively for calculating the electronic structure
of alloys, did not yet exist.
The many-body CPA paved the way for dynamical mean-field theory (DMFT)
which came nearly 30 years later and gave the first satisfactory
theory of the metal-insulator transition. DMFT is now used routinely
for realistic calculations of the electronic structure of
strongly-correlated electron systems. These developments, together
with some personal reminiscences of John Hubbard from our student days
onwards, form the first part of the present talk. There have been two
major revivals of interest in the Hubbard model since the early days.
The first followed the discovery in 1986 of high temperature
superconductivity in doped copper oxides and Anderson's immediate use
of the Hubbard model as a vehicle for his resonating valence bond
theory of these materials. The relevance of the Hubbard model to high
temperature superconductivity is still controversial and will be
discussed. The second Hubbard model renaissance came in the 2000s with
its experimental realisation by cold atoms in optical lattices. Recent
developments will be discussed.