arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2108.01258cond-mat.stat-mech
收藏

体心立方晶格上的阻挫伊辛模型

The frustrated Ising model on the body-centered cubic lattice

M. Schmidt, G. L. Kohlrausch, F. M. Zimmer

摘要:

体心立方(bcc)晶格上具有第一($J_1$)和第二($J_2$)相邻相互作用的伊辛模型的最新结果表明,该模型可以承载强挫折的特征,包括肖特基异常和剩余熵,以及自旋液体状相[E. Jurčišinová和M. Jurčišin,Phys.Rev.B,101214443(2020)]。基于这些发现,我们用团簇平均场方法研究了该模型的相变和热力学。在这个晶格中,调谐$g=J_2/J_1$导致在阻挫最大值$g=2/3$处反铁磁(AF)和超反铁磁(SAF)相之间的基态转变。虽然有序温度降低为$g \to 2/3$,我们的研究结果表明,没有任何肖特基异常和剩余熵,在良好的协议与蒙特卡罗模拟。我们还发现AF和SAF阶段之间的直接过渡,排除了存在的自旋液体状状态。此外,集群平均场的结果支持的情况下,只有连续的相变之间的顺磁状态和低温长程序。因此,我们的研究结果表明,在热力学和相变的性质,这可以归因于较高的维数的体心立方晶格中没有强烈的挫折效应。

英文摘要:

Recent results for the Ising model with first ($J_1$) and second ($J_2$) neighbour interactions on the body-centered cubic (bcc) lattice suggest that this model can host signatures of strong frustration, including Schottky anomalies and residual entropy, as well as, a spin-liquid-like phase [E. Jurčišinová and M. Jurčišin, Phys. Rev. B, 101 214443 (2020)]. Motivated by these findings, we investigate phase transitions and thermodynamics of this model using a cluster mean-field approach. In this lattice, tuning $g=J_2/J_1$ leads to a ground-state transition between antiferromagnetic (AF) and superantiferromagnetic (SAF) phases at the frustration maximum $g=2/3$. Although the ordering temperature is reduced as $g \to 2/3$, our findings suggest the absence of any Schottky anomaly and residual entropy, in good agreement with Monte Carlo simulations. We also find a direct transition between AF and SAF phases, ruling out the presence of the spin-liquid-like state. Furthermore, the cluster mean-field outcomes support a scenario with only continuous phase transitions between the paramagnetic state and the low-temperature long-range orders. Therefore, our results indicate the absence of strong frustration effects in the thermodynamics and in the nature of phase transitions, which can be ascribed to the higher dimensionality of the bcc lattice.

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。

↑