arXiv:1301.5719 · Physical Review B
Realization of higher Wess-Zumino-Witten models in spin chains
Frédéric Michaud, Salvatore R. Manmana, Frédéric Mila
Abstract
Building on the generalization of the exactly dimerized Majumdar-Ghosh ground state to arbitrary spin $S$ for the Heisenberg chain with a three-site term $({\mathbf{S}}_{i\ensuremath{-}1}\ifmmode\cdot\else\textperiodcentered\fi{}{\mathbf{S}}_{i})({\mathbf{S}}_{i}\ifmmode\cdot\else\textperiodcentered\fi{}{\mathbf{S}}_{i+1})+\text{H.c.}$, we use density-matrix renormalization group simulations and exact diagonalizations to determine the nature of the dimerization transition for $S=1$, $3/2$, and 2. The resulting central charge and critical exponent are in good agreement with the $\text{SU}{(2)}_{k=2S}$ Wess-Zumino-Witten values $c=3k/(2+k)$ and $\ensuremath{\eta}=3/(2+k)$. Since the three-site term that induces dimerization appears naturally if exchange interactions are calculated beyond second order, these results suggest that $\text{SU}{(2)}_{k>1}$ Wess-Zumino-Witten models might finally be realized in actual spin chains.