Accueil du site > Séminaires > Séminaires 2006 > How to have fun with two-dimensional frustrated ferromagnets...
Mardi 26/09/2006 - 14H00
Nic Shannon (Bristol University)
par
- 26 septembre 2006
The theoretical study of two—dimensional ``spin liquids’’ — quantum
magnets which remain disordered at the very lowest temperatures — has
mostly been confined to models with competing or frustrated
antiferromagnetic (AF) interactions.
The resulting ground states typically involve strong singlet bonds
between spins, which give rise to a gap in the spin excitation spectrum.
None the less, the best characterized experimental realization of
a spin liquid is believed to occur in two—dimensional
films of solid He, where the interactions between spins are
predominantly ferromagnetic (FM), and the resulting state is gapless.
Here we consider whether the breakdown of long ranged FM order
offers a new route unconventional magnetic ground states in two dimensions,
considering in detail the case of the square lattice frustrated ferromagnet.