Physical review. B, Condensed matter
S=1 antiferromagnetic Heisenberg chain with an axial-symmetry-breaking anisotropy
Tiôru Sakai, Minoru Takahashi
Abstract
The ground state of the S=1 antiferromagnetic Heisenberg chain with an axial-symmetry-breaking anisotropy ${\mathit{E}\mathit{tsum}}_{\mathit{j}}$ [(${\mathit{S}}_{\mathit{j}}^{\mathit{x}}$${)}^{2}$-(${\mathit{S}}_{\mathit{j}}^{\mathit{y}}$${)}^{2}$] is studied by the finite-size scaling and phenomenological renormalization-group technique based on numerical diagonalizations up to N=14. It is found that two phase transitions exist at ${\mathit{E}}_{\mathit{c}1}$=0.20\ifmmode\pm\else\textpm\fi{}0.01 and ${\mathit{E}}_{\mathit{c}2}$=1.71\ifmmode\pm\else\textpm\fi{}0.01, and both transitions belong to the same universality class as the two-dimensional Ising model.