Do spin glasses order in a field?
Prof. Helmut Katzgraber (Texas A&M University and ETH Zurich)

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 systems. 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 an overview of the properties of spin glasses, I discuss recent results on the existence of a spin-glass state in an external field. Our results show that the spin-glass state is not stable in a field for short-range systems below the upper critical dimension.