arXiv:cond-mat/9809138 · Journal of Physics A Mathematical and General
Magnetization plateau and quantum phase transition of theS= ½ trimerizedXXZspin chain
Kiyomi Okamoto, Atsuhiro Kitazawa
Abstract
We study the plateau of the magnetization curve at M = M s /3 ( M s is the saturation magnetization) of the S = ½ trimerized XXZ spin chain. By examining the level crossing of low-lying excitations obtained from the numerical diagonalization, we precisely determine the phase boundary between the plateau state and the no-plateau state on the - t plane, where denotes the XXZ anisotropy and t the magnitude of the trimerization. This quantum phase transition is of the Berezinskii-Kosterlitz-Thouless type.