Showing papers by "Shoji Yamamoto published in 1996"
TL;DR: In this paper, the low-temperature properties of S = 1 and 1/2 alternating spin chains with antiferromagnetic nearest-neighbor exchange couplings using analytical techniques as well as a quantum Monte Carlo method were investigated.
Abstract: We study the low-temperature properties of S=1 and 1/2 alternating spin chains with antiferromagnetic nearest-neighbor exchange couplings using analytical techniques as well as a quantum Monte Carlo method. The spin-wave approach predicts two different low-lying excitations, which are gapped and gapless, respectively. The structure of low-lying levels is also discussed by perturbation theory in the strength of the Ising anisotropy. These analytical findings are compared with the results of quantum Monte Carlo calculations and it turns out that spin-wave theory well describes the present system. We conclude that the quantum ferrimagnetic chain exhibits both ferromagnetic and antiferromagnetic aspects.
53 citations
25 citations
TL;DR: In this article, the ground-state spin-spin correlation function and an excitation gap immediately above the ground state were calculated for chains up to 512 spins and the large-separation correlations were well fitted to the two-dimensional Ornstein-Zernike form.
17 citations