Temperature-field phase diagram of the two-dimensional dipolar Ising ferromagnet
Temperature-field phase diagram of the two-dimensional dipolar Ising ferromagnet
复制标题
二维偶极伊辛铁磁体的温度场相图
DOI：
10.1103/physreve.98.062126
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发表时间：
2018
影响因子：
2.4
通讯作者：
Nishino Masamichi
中科院分区：
文献类型：
--
作者：
Komatsu Hisato;Nonomura Yoshihiko;Nishino Masamichi
本文研究了具有交换常数与偶极常数之比的二维偶极伊辛铁磁体的场致相变，发现在低温无磁场条件下，二维偶极伊辛铁磁体呈现出一个晶格单元宽度的条形有序相。利用平均场近似和蒙特卡罗（MC）方法，结合随机截止算法（一种模拟方法），给出了温度场相图。在MC研究中，对取向顺序和结构因子进行了评价。二阶过渡点由有限尺度分析确定，一阶过渡点由能量直方图分析确定。虽然MF相图和MC相图都由多个条形有序相组成的宽区域和它们之间以复杂条形图为特征的窄区域组成，但它们在可能的相和相边界上表现出定性和定量的差异。在MF相图中，三个主要的条纹有序相呈嵌套结构，而在MC相图中，两个主要的条纹有序相是分开的，这导致了取向顺序的特征性场诱导重入转变。据我们所知，这是第一次观察到偶极伊势铁磁体的重入相转变。
We study field-induced phase transitions in the two-dimensional dipolar Ising ferromagnet with a specific ratio between the exchange and dipolar constants,, which exhibits a stripe-ordered phase with the width of one lattice unit at low temperatures without magnetic field. By using a mean-field (MF) approximation and a Monte Carlo (MC) method with the stochastic-cutoff algorithm, which is ansimulation method, we show the temperature-field phase diagrams. In the MC study the orientational order and the structure factor are evaluated. Second-order transition points are determined by a finite-size-scaling analysis and first-order transition points are identified by the analysis of the energy histogram. Although both the MF and MC phase diagrams consist of wide regions of several stripe-ordered phases and narrow regions between them characterized by complicated stripe patterns, they show qualitative and quantitative differences in possible phases and phase boundaries. In the MF phase diagram, three main stripe-ordered phases exhibit a nesting structure, while in the MC phase diagram, two main stripe-ordered phases are located separately, which causes a characteristic field-induced reentrant transition of the orientational order. To our knowledge, this is the first observation of the reentrant phase transition in the dipolar Ising ferromagnet.