Exotic phases and phase transitions in quantum magnetism

Michael Hermele, University of Colorado

Classifying and characterizing states of matter and phase transitions between them is one of the most basic tasks of condensed matter physics. In systems with only bosonic degrees of freedom, the "standard" approach to this task is based on construction of a Landau free energy in terms of one or more order parameters. Exotic phases are simply those for which this approach is insufficient.  

As particularly simple strongly correlated systems, quantum magnets are a good testing ground to explore exotic states of matter. In this tutorial talk, I will survey the current understanding of exotic states in two- and three-dimensional quantum magnets, and highlight some of the major open issues.