Colloquium on June 26, 2006

Roderich Moessner
CNRS and ENS Paris

Frustration, liquidity and exotic order

A large part of modern physics is devoted to the study of systems which -- for one reason or another -- do not enter a simple ordered state at low temperature; frequently used names for such systems include 'exotic', 'correlated', 'complex' or 'strongly fluctuating'.

This talk is about a class of systems in which it is geometric frustration -- the competition between interactions or degrees of freedom -- which prevents the formation of a simple ordered low-temperature state. This class comprises a wide range of theoretical models as well as experimental systems ranging from magnetic compounds to artificial nanostructures.

I will discuss how frustrated systems come to display a wide range of exotic phenomena, including liquid, ice and topological phases. These can exhibit fractionalised quasiparticles and even act as an ether for dynamically generated (`emergent') artificial photons. Possible applications, most saliently in the field of topological quantum computing, will also be discussed.