We study the surface phase diagram of the three-dimensional kinetic Ising model below the equilibrium critical point subjected to a periodically oscillating magnetic field. Changing the surface interaction strength as well as the period of the external field, we obtain a nonequilibrium surface phase diagram that in parts strongly resembles the corresponding equilibrium phase diagram, with an ordinary transition, an extraordinary transition, and a surface transition. These three lines meet at a special transition point. For weak surface couplings, however, the surface does not order. These results are found to remain qualitatively unchanged when using different single-spin flip dynamics.

Synthetic antiferromagnets with strong perpendicular anisotropy can be modeled by layered Ising antiferromagnets. Accounting for the fact that in the experimental systems the ferromagnetic layers, coupled antiferromagnetically via spacers, are multilayers, we propose a description through Ising films where ferromagnetic stacks composed of multiple layers are coupled antiferromagnetically. We study the equilibrium and non-equilibrium properties of these systems where we vary the number of layers in each stack. Using numerical simulations, we construct equilibrium temperature−magnetic field phase diagrams for a variety of cases. We find the same dominant features (three stable phases, where one phase boundary ends in a critical end point, whereas the other phase boundary shows a tricritical point at which the transition changes from first to second order) for all studied cases. Using time-dependent quantities, we also study the ordering processes that take place after a temperature quench. The nature of long-lived metastable states are discussed for thin films, whereas for thick films we compute the surface autocorrelation exponent.PACS numbers: 75.10. Hk,75.30.Kz,75.40.Mg Heterostructures formed by ferromagnetic multilayers that are coupled antiferromagnetically via spacers have a wide range of possible applications, ranging from high-density storage technology to spintronic devices. 1-4 Cases with strong perpendicular anisotropy (as encountered, for example, in [Co/Pt]/Ru or [Co/Pt]/NiO with ferromagnetic [Co/Pt] multilayers)have been the objects of intensive studies, both experimentally 5-10 and theoretically. 9,[11][12][13][14][15][16] Due to the overall structure of these antiferromagnetically coupled multilayers, they are sometimes referred to as synthetic or artificial metamagnets. In phenomenological approaches, these systems are commonly modeled by layered antiferromagnets where a ferromagnetic multilayer is described by a single variable, namely the total magnetization of the multilayer. For strong perpendicular anisotropy, this naturally leads to the description via an Ising metamagnet where layers with ferromagnetic in-layer interactions are coupled antiferromagnetically. Ising bulk metamagnets have been the subject of many studies in the past and their properties are well understood by now. 17-30 Surprises show up, however, when studying Ising metamagnets in thin film geometry. In systems with an even number of layers and a magnetic field applied perpendicular to the surfaces, the temperature-field phase diagram exhibits a new phase in addition to the two phases of the bulk system (the low field antiferromagnetic and the high field paramagnetic phases): for intermediate field strengths, the surface layer, which is magnetized oppositely to the applied magnetic field in the ground state, aligns with the magnetic field. The phase transition between the antiferromagnetic phase and this intermediate phase is discontinuous and ends in a critical end point. 31The characterization of the ferromagnetic multil...