Resonating color state in the large-S kagome antiferromagnet
Institut Néel, Grenoble
Lundi 17/10/2011, 14:00
Salle Claude Itzykson, Bât. 774, Orme des Merisiers
The large-S approach (leading e.g. to spin-waves in ordered magnets) breaks down in
the two-dimensional kagome antiferromagnet, reflecting the large classical degeneracy of the ground state. I will argue that the low-energy modes responsible for this breakdown can be described by non-linear oscillators which, when quantized, lead to a
dynamics within the classical degenerate manifold, well described by an effective gauge theory. It turns out that these quantum fluctuations select the Néel order at zero temperature (order-by-disorder). The order is, however, unconventional in that it has some gauge excitations in addition to spin-waves. We predict that these
excitations provide a new temperature scale above which the system is "critical" in some energy range.