arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1206.6534cond-mat.stat-mech
收藏

磁场作用下各向异性简立方晶格上的伊辛反铁磁体

The Ising antiferromagnet on an anisotropic simple cubic lattice in the presence of a magnetic field

Octavio D. R. Salmon, Minos A. Neto, J. Roberto Viana, Igor T. Padilha, J. R. de Sousa

摘要:

研究了在均匀纵向磁场$H$中具有竞争相互作用的三维各向异性最近邻Ising模型.该模型由$x(z)$方向的铁磁相互作用$J_{x}(J_{z})$和$y$方向的反铁磁相互作用$J_{y}$组成。我们比较了我们的计算在一个有效场理论的集群与四个自旋(EFT-4)在简单的立方(SC)晶格与传统的蒙特卡罗(MC)模拟。对$λ_{1}=J_{y}/J_{x} (λ_{2}=J_{z}/J_{x})=1$(各向异性sc)的特殊情况,得到了$h-k_{B}T/J_{x}$平面内的相图($h=H/J_{x}$)。我们的研究结果表明,二阶边界的所有值的$H$的特定情况下$λ_{2}=0$(正方形晶格),而在情况$λ_{1}=λ_{2}=1$,我们观察到一阶和二阶相变的低温和高温极限,分别与存在的三临界点。用EFT-4在低温下观察到一个重入行为,与MC的结果相反。

英文摘要:

We have studied the anisotropic three-dimensional nearest-neighbor Ising model with competitive interactions in an uniform longitudinal magnetic field $H$. The model consists of ferromagnetic interaction $J_{x}(J_{z})$ in the $x(z)$ direction and antiferromagnetic interaction $J_{y}$ in the $y$ direction. We have compared our calculations within a effective-field theory in clusters with four spins (EFT-4) in the simple cubic (sc) lattice with traditional Monte Carlo (MC) simulations. The phase diagrams in the $h-k_{B}T/J_{x}$ plane ($h=H/J_{x}$) were obtained for the particular case $λ_{1}=J_{y}/J_{x} (λ_{2}=J_{z}/J_{x})=1$ (anisotropic sc). Our results indicate second-order frontiers for all values of $H$ for the particular case $λ_{2}=0$ (square lattice), while in case $λ_{1}=λ_{2}=1$, we observe first- and second-order phase transitions in the low and high temperature limits, respectively, with presence of a tricritical point. Using EFT-4, a reentrant behavior at low temperature was observed in contrast with results of MC.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑