arXiv:cond-mat/9801288 · Physical review. B, Condensed matter
Critical exponent in the magnetization curve of quantum spin chains
Tôru Sakai, Minoru Takahashi
Abstract
The ground-state magnetization curve around the critical magnetic field ${H}_{c}$ of quantum spin chains with a spin gap is investigated. We propose a size scaling method to estimate the critical exponent \ensuremath{\delta} defined as $m\ensuremath{\sim}|H\ensuremath{-}{H}_{c}{|}^{1/\ensuremath{\delta}}$ from finite cluster calculation. The applications of the method to the $S=1$ antiferromagnetic chain and $S=1/2$ bond-alternating chain lead to a common conclusion that $\ensuremath{\delta}=2.$ The same result is derived for both edges of the magnetization plateau of the $S=3/2$ antiferromagnetic chain with single-ion anisotropy.