Field Induced Long Range Ordering in a Spin 1 Quasi-One-Dimensional Heisenberg Antiferromagnet

Ronald Zinke, J. Schulenburg, Johannes Richter

S. Rufo, Griffith Mendonça, J. A. Plascak +1 more

The ground-state properties of the quasi-one-dimensional spin-$1/2$ antiferromagnetic Heisenberg model is investigated by using a variational method. Spins on chains along the $x$ direction are antiferromagnetically coupled with exchange $J>0$, while spins between chains in the $y$ direction are coupled either ferromagnetically (${J}^{\ensuremath{'}}<0$) or antiferromagnetically (${J}^{\ensuremath{'}}>0$). The staggered and the colinear antiferromagnetic magnetizations are computed and their dependence on the anisotropy parameter $\ensuremath{\lambda}=|{J}^{\ensuremath{'}}|/J$ is analyzed. It is found that an infinitesimal interchain coupling parameter is sufficient to stabilize a long-range order with either a staggered magnetization ${m}_{s}$ (${J}^{\ensuremath{'}}>0$) or a colinear antiferromagnetic magnetization ${m}_{caf}$ (${J}^{\ensuremath{'}}<0$), both behaving as $\ensuremath{\simeq}{\ensuremath{\lambda}}^{1/2}$ for $\ensuremath{\lambda}\ensuremath{\rightarrow}0$.

Dongfang Chen

The magnetic order of a special quasi-one-dimensional Heisenberg antiferromagnetic spin model with numerical density matrix renormalization groups is discussed. The ground energy per unit cell, spin correlation function and the spin gap are calculated. Results show that the quasi-one-dimensional spin system has magnetic long-rang order under ground state and the spin correlation on chain is short-rang.

Tohru Koma

Chitoshi Yasuda, Synge Todo, Munehisa Matsumoto +1 more

Effects of the site dilution on spin-gapped Heisenberg antiferromagnets with $S=\frac{1}{2}$ and $S=1$ on a square lattice of coupled dimerized chains are investigated by means of the quantum Monte Carlo method. It is found that effective magnetic moments induced around the diluted sites exhibit the antiferromagnetic long-range order in the medium of spin-singlet pairs. Their microscopic structure is examined in detail and important roles of higher dimensionality other than one in the phenomenon are discussed.

B. Lake, Anup Kumar Bera, Fabian H. L. Eßler +6 more