IFISUR   23398
INSTITUTO DE FISICA DEL SUR
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Charla Invitada: "Symmetry breaking phase transitions and pattern formation in curved space"
Autor/es:
VEGA DA
Lugar:
Buenos Aires
Reunión:
Simposio; FRONTIERS IN PHYSICAL SCIENCES. HUMBOLDT KOLLEG.; 2016
Institución organizadora:
ICAS - Max Planck - Alexander von Humboldt Foundation.
Resumen:
Nucleation and growth and spinodal decomposition are the dominant relaxationmechanisms driving symmetry breaking phase transitions. Due to causality, thedirections of symmetry breaking are different in different regions of space and defectsare unavoidably created.Here we study the processes of phase separation and self-organization of blockcopolymer thin films deposited on topographically patterned curved substrates.Experiments and a phase field Guinzburg-Landau approach are employed to analyze thecoupling between textures with hexagonal and smectic symmetries and the local meanand Gaussian curvatures of the substrate. Mechanisms of phase separation, defectformation and defect dynamics are found to strongly deviate from their counterparts inflat space. At the onset of a phase transition, in crystalline systems the early density ofdefects becomes highly inhomogeneous and even a single growing crystal can producevarying densities of defects. In systems with smectic symmetry, the substrate's curvatureproduces out-of-plane deformations of the thin film such that the kinetics of orderingand equilibrium configurations are also controlled by the underlying geometry. Thus,non-euclidean geometry is a robust mechanisms to stabilize exotic structures of defects.In addition, we also demonstrate experimentally, theoretically, and through simulationsthat defects in free-standing membranes can act as sources of Gaussian curvature, whichcan have important implications in the use of smectic films in the development of noveldefect-prescribed shapes.