A test of the bosonic spinon theory for the triangular antiferromagnet spectrum

A. MEZIO; C. N. SPOSETTI; L. O. MANUEL; A. E. TRUMPER

EUROPHYSICS LETTERS

EPL ASSOCIATION

Lugar: Bologna; Año: 2011 vol. 94 p. 47001 - 47006

0295-5075

We compute the dynamical structure factor of the spin- 1/2 triangular Heisenberg model using the mean-field Schwinger boson theory. We find that a reconstructed dispersion, resulting from a non-trivial redistribution of the spectral weight, agrees quite well with the spin excitation spectrum recently found with series expansions. In particular, we recover the strong renormalization with respect to linear spin wave theory along with the appearance of roton-like minima. Furthermore, near the roton-like minima the contribution of the two spinon continuum to the static structure factor is about 40% of the total weight. By computing the density-density dynamical structure factor, we identify an unphysical weak signal of the spin excitation spectrum with the relaxation of the local constraint of the Schwinger bosons at the mean-field level. Based on the accurate description obtained for the static and dynamic ground-state properties, we argue that the bosonic spinon theory should be considered seriously as a valid alternative to interpret the physics of the triangular Heisenberg model.