CONICET | Buscador de Institutos y Recursos Humanos

We present a numerical study of thelocalization-delocalization transition of the interface between magneticdomains of different orientation, in both Ising and Blume-Capel [1] magnetsconfined between two walls separated by a distance $L$, where short-rangecompetitive surface magnetic fields act. So, samples are assumed to have a sizeLxM, L being the width and M the length, respectively. Thelocalization-delocalization transition of the interface becomes a true wetting phasetransition when the thermodynamic limit (L → ∞, M → ∞) is properly taken, as itfollows from the scaling theory [2].By considering a fixed (quenched) vacancies ornonmagnetic impurities along the centre (i.e. for x = L/2) of an Ising samplewe found that wetting transition can be of either of first- or second-order,depending on the concentration of vacancies. While first-order transitions areprecisely located by means of thermodynamic integration methods [3], second-ordertransitions are accurately determined by using a suitable scaling theory [2].In this way, at the intersection between second- and first-order lines we foundtricritical wetting points. On the other hand, we also considered both standardand modified Blume-Capel [1] models in order to gain insight on the role ofmobile impurities. Here, tricritical wetting is also found but for a tinyconcentration of impurities.So, our study concludes that a proper densityof both quenched and mobile nonmagnetic impurities can effectively cause thepinning-depinning transition of magnetic interfaces. Both cases are fullydiscussed and the relevance of the results for the design of nano-magneticstorage devices is stressed. [1] M.Blume, Phys. Rev. B., V141, 517 (1966). H. W. Capel, Physica, V32 966 (1966).[2] EzequielV. Albano and Kurt Binder. Phys. Rev. Lett. V109, 036101 (2012).[3] Marta L. Trobo, Ezequiel V. Albano, and Kurt Binder. Phys. Rev.E V90, 022406 (2014).