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arXiv 0807.0150cond-mat.stat-mech
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双曲格点上J1-J2伊辛模型的三临界点

Tricritical point of J1-J2 Ising model on hyperbolic lattice

R. Krcmar, T. Iharagi, A. Gendiar, T. Nishino

摘要:

利用角转移矩阵重整化群方法研究了双曲晶格上二维阻挫伊辛模型的铁磁-顺磁相变.该模型包含铁磁最近邻相互作用J_1和竞争反铁磁相互作用J_2。当κ= J_2 / J_1小于0.203时,观察到了类平均场的二级相变。在0.203 < κ< 1/4的范围内,自发磁化强度在相变温度下是不连续的。这种三临界行为表明双曲晶格上的相变不一定总是类似平均场的。

英文摘要:

A ferromagnetic-paramagnetic phase transition of the two-dimensional frustrated Ising model on a hyperbolic lattice is investigated by use of the corner transfer matrix renormalization group method. The model contains ferromagnetic nearest-neighbor interaction J_1 and the competing antiferromagnetic interaction J_2. A mean-field like second-order phase transition is observed when the ratio κ= J_2 / J_1 is less than 0.203. In the region 0.203 < κ< 1/4, the spontaneous magnetization is discontinuous at the transition temperature. Such tricritical behavior suggests that the phase transitions on hyperbolic lattices need not always be mean-field like.

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