Costabile Emanuel, de Sousa J Ricardo
Departamento de Física, Universidade Federal do Amazonas, 3000, Japiim, 69077-000, Manaus-AM, Brazil.
Phys Rev E Stat Nonlin Soft Matter Phys. 2012 Jan;85(1 Pt 1):011121. doi: 10.1103/PhysRevE.85.011121. Epub 2012 Jan 13.
The dynamical phase transitions of the kinetic Ising model in the presence of a random magnetic field with a bimodal probability distribution is studied by using effective-field theory (EFT) with correlations. We have used a Glauber-type stochastic dynamic to describe the time evolution of the system, where the system strongly depends on the H≡√<H(i)(2)>(c) root mean square deviation of the magnetic field. The EFT dynamic equation is given for the simple cubic lattice (z=6), and the dynamic order parameter is calculated. The system presents ferromagnetic and paramagnetic states for low and high temperatures, respectively. Our results predict first-order transitions at low temperatures and large disorder strengths, which corresponds to the existence of a nonequilibrium tricritical point (TCP) in a phase diagram in the T-H plane. We compare the results with the equilibrium phase diagram, where only the first-order line is different. Our qualitative results are compatible with recent Monte Carlo simulations.
利用含关联的有效场理论（EFT）研究了具有双峰概率分布的随机磁场存在下动力学伊辛模型的动力学相变。我们采用了一种格劳伯型随机动力学来描述系统的时间演化，其中系统强烈依赖于磁场的均方根偏差(H≡\sqrt{\langle H(i)^2\rangle})。给出了简单立方晶格（配位数(z = 6)）的EFT动力学方程，并计算了动力学序参量。系统在低温和高温下分别呈现铁磁态和顺磁态。我们的结果预测在低温和大无序强度下存在一级相变，这对应于(T - H)平面相图中一个非平衡三临界点（TCP）的存在。我们将结果与平衡相图进行比较，其中只有一级相变线不同。我们的定性结果与最近的蒙特卡罗模拟结果相符。
