Critical behavior of anisotropic Heisenberg mixed-spin chains in a field

Abstract

We numerically investigate the critical behavior of the spin-(1,1/2)\nHeisenberg ferrimagnet with anisotropic exchange coupling in a magnetic field.\nA quantized magnetization plateau as a function of the field, appearing at a\nthird of the saturated magnetization, is stable over whole the\nantiferromagnetic coupling region. The plateau vanishes in the ferromagnetic\ncoupling region via the Kosterlitz-Thouless transition. Comparing the quantum\nand classical magnetization curves, we elucidate what are essential quantum\neffects.\n