SEMINARIO DE FISICA TEORICA I Y II

Titulo:         New insights from one-dimensional spin glasses
Conferenciante: Helmut Katzgraber (ETH Zurich, Suiza)
Dia y hora:     9, 14:15 (Aula 8A)

Resumen:

Spin glasses are paradigmatic models that deliver concepts relevant for
a variety of systems. However, despite ongoing research spanning
several decades in the area of glassy systems, there remain
many fundamental open questions. Rigorous analytical results are
difficult to obtain for spin-glass models, in particular for realistic
short-range models. Therefore large-scale numerical simulations are
the tool of choice. Concepts from the solution of the mean-field
model, such as ergodicity breaking, aging, ultrametricity, and the
existence of an instability line at finite magnetic fields known as
the Almeida-Thouless line, have been applied to realistic short-range
spin-glass models as well as to fields as diverse as structural
biology, geology, computer science and even financial analysis.
After presenting a brief overview of the properties of spin glasses,
I discuss a one-dimensional long-range Ising spin-glass model with
power-law interactions, where one can tune effectively the space
dimension.  Using this model I analyze different properties of spin
glasses and, in particular, the existence of the Almeida-Thouless line,
i.e., the existence of a spin-glass state in a field.  Our results
show that the spin-glass state is not stable in a field for short-range
systems below the upper critical dimension.