Abstract
Enrique Rico Ortega (University of Vienna, Austria)
Valence-bond states: Link models
An isotropic anti-ferromagnetic quantum state on a square lattice is
characterized by symmetry arguments only. By construction, this
quantum state is the result of an underlying valence bond structure
without breaking any symmetry in the lattice or spin spaces. A
detailed analysis of the correlations of the quantum state is given
(using a mapping to a 2D classical statistical model and methods in
field theory like mapping to the non-linear sigma model or
bosonization techquines) as well as the results of numerical
treatments (regarding exact diagonalization and variational methods).
Finally, the physical relevance of the model is motivated. A
comparison of the model to known anti-ferromagnetic Mott-Hubbard
insulators is given by means of the two-point equal-time correlation
function obtained (i) numerically from the suggested state and (ii)
experimentally from neutron scattering on cuprates in the
anti-ferromagnetic insulator phase.
Reference: Annals Phys. 324:1875-1896 (2009). arXiv:0811.1049