Keskin Mustafa, Ertaş Mehmet
Department of Physics, Erciyes University, 38039 Kayseri, Turkey.
Phys Rev E Stat Nonlin Soft Matter Phys. 2009 Dec;80(6 Pt 1):061140. doi: 10.1103/PhysRevE.80.061140. Epub 2009 Dec 30.
The magnetic properties of a nonequilibrium mixed spin-2 and spin-5/2 Ising ferrimagnetic system with a crystal-field interaction (D) in the presence of a time-varying magnetic field on a hexagonal lattice are studied by using the Glauber-type stochastic dynamics. The model system consists of two interpenetrating sublattices with sigma=2 and S=5/2. The Hamiltonian model includes intersublattice, intrasublattice, and crystal-field interactions. The intersublattice interaction is considered antiferromagnetic to have a simple but interesting model of a ferrimagnetic system. The set of mean-field dynamic equations is obtained by employing the Glauber transition rates. First, we investigate the time variations in average sublattice magnetizations to find the phases in the system, and the temperature dependence of the dynamic sublattice magnetizations to characterize the nature (continuous or discontinuous) of the phase transitions and to obtain the dynamic phase transition points. Then, we study the temperature dependence of the total magnetization to find the dynamic compensation points as well as to determine the type of behavior. We also investigate the effect of a crystal-field interaction and the exchange couplings between the nearest-neighbor pairs of spins on the compensation phenomenon and present the dynamic phase diagrams. According to values of Hamiltonian parameters, the paramagnetic, the nonmagnetic, and the four different ferrimagnetic fundamental phases, seven different mixed phases, and the compensation temperature, or the N-type behavior in the Néel classification nomenclature exist in the system. A comparison is made with the results of the available mixed spin Ising systems.
利用格劳伯型随机动力学研究了具有晶体场相互作用（D）的非平衡混合自旋-2和自旋-5/2伊辛亚铁磁系统在六角晶格上随时间变化磁场作用下的磁特性。该模型系统由两个相互贯穿的子晶格组成，其自旋量子数分别为σ = 2和S = 5/2。哈密顿模型包括子晶格间、子晶格内以及晶体场相互作用。子晶格间相互作用被认为是反铁磁的，以得到一个简单但有趣的亚铁磁系统模型。通过采用格劳伯跃迁速率得到了平均场动力学方程组。首先，我们研究平均子晶格磁化强度的时间变化以找出系统中的相，以及动力学子晶格磁化强度的温度依赖性，以表征相变的性质（连续或不连续）并获得动态相变点。然后，我们研究总磁化强度的温度依赖性以找出动态补偿点并确定行为类型。我们还研究了晶体场相互作用以及最近邻自旋对之间的交换耦合对补偿现象的影响，并给出了动态相图。根据哈密顿参数的值，系统中存在顺磁、非磁、四种不同的亚铁磁基本相、七种不同的混合相以及补偿温度，或者在奈耳分类命名法中的N型行为。并与现有混合自旋伊辛系统的结果进行了比较。
