title: Phase transitions in a three-dimensional kinetic spin-1/2 Ising model with random field: effective-field-theory study.
abstract: 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.
authors.affiliation: Departamento de Física, Universidade Federal do Amazonas, 3000, Japiim, 69077-000, Manaus-AM, Brazil.
authors.forename: Emanuel
authors.initials: E
authors.lastname: Costabile
authors.forename: J Ricardo
authors.initials: JR
authors.lastname: de Sousa
mesh_terms: D003198:Computer Simulation; D007700:Kinetics; D008956:Models, Chemical; D008958:Models, Molecular; D015233:Models, Statistical; D044367:Phase Transition; D012996:Solutions / Q000737:chemistry* / Q000528:radiation effects*; D013113:Spin Labels
chemical_list: D012996:Solutions; D013113:Spin Labels