arXiv:cond-mat/9806344 · Journal of Physics Condensed Matter
Combination of ferromagnetic and antiferromagnetic features in Heisenberg ferrimagnets
Shoji Yamamoto, Takahiro Fukui, Klaus Maisinger, Ulrich Schollwöck
Abstract
We investigate the thermodynamic properties of Heisenberg ferrimagnetic mixed-spin chains both numerically and analytically with particular emphasis on the combination of ferromagnetic and antiferromagnetic features. Employing a new density-matrix renormalization-group technique as well as a quantum Monte Carlo method, we reveal the overall thermal behaviour: at very low temperatures, the specific heat and the magnetic susceptibility multiplied by the temperature behave like and , respectively, whereas at intermediate temperatures, they exhibit a Schottky-like peak and a minimum, respectively. Developing the modified spin-wave theory, we complement the numerical findings and give precise estimates for the low-temperature behaviour.