Departamento de Física, Universidade Federal de Santa Maria, 97105-900 Santa Maria, RS, Brazil.
Instituto de Física, Universidade Federal de Mato Grosso do Sul, 79070-900 Campo Grande, MS, Brazil.
Phys Rev E. 2019 Jan;99(1-1):012134. doi: 10.1103/PhysRevE.99.012134.
We investigate the role of a transverse field on the Ising square antiferromagnet with first (J_{1}) and second (J_{2}) neighbor interactions. Using a cluster mean-field approach, we provide a telltale characterization of the frustration effects on the phase boundaries and entropy accumulation process emerging from the interplay between quantum and thermal fluctuations. We found that the paramagnetic (PM) and antiferromagnetic phases are separated by continuous phase transitions. On the other hand, continuous and discontinuous phase transitions, as well as tricriticality, are observed in the phase boundaries between PM and superantiferromagnetic phases. A rich scenario arises when a discontinuous phase transition occurs in the classical limit while quantum fluctuations recover criticality. We also find that the entropy accumulation process predicted to occur at temperatures close to the quantum critical point can be enhanced by frustration. Our results provide a description for the phase boundaries and entropy behavior that can help to identify the ratio J_{2}/J_{1} in possible experimental realizations of the quantum J_{1}-J_{2} Ising antiferromagnet.
我们研究了横场对具有第一（J_1）和第二（J_2）近邻相互作用的伊辛正方形反铁磁体的作用。使用团簇平均场方法，我们对量子和热涨落相互作用产生的相界和熵积累过程中的挫折效应进行了明显的特征描述。我们发现，顺磁（PM）相和反铁磁相之间通过连续相变分离。另一方面，在 PM 和超反铁磁相之间的相界处观察到连续和不连续相变以及三临界点。当经典极限中发生不连续相变而量子涨落恢复临界时，会出现丰富的情况。我们还发现，在接近量子临界点的温度下预测的熵积累过程可以通过挫折来增强。我们的结果提供了对相界和熵行为的描述，有助于确定量子 J_1-J_2 伊辛反铁磁体在可能的实验实现中的 J_2/J_1 比值。
