title: Forbidden walls.
abstract: In this paper the presence of periodic twist-bend walls in the upper vicinity of the Frèedericksz critical point of a nematic calamitic sample is reported. According to the existing theory, the formation of these structures could not happen in this region of the magnetic field. The length of the periodicity of these walls as well as the time spent with their formation have been measured, and it was demonstrated that the coherent motion of the nematic material cannot drive their construction. We assume that the mechanism responsible for their appearance results from the magnification of some selected random fluctuations occurring at the neighborhood of the Frèedericksz critical point.
authors.affiliation: Departamento de Fisica, Universidade Estadual de Londrina, Campus Universitario, 86051-970, Londrina (PR), Brazil.
authors.forename: M
authors.initials: M
authors.lastname: Simões
authors.forename: A J
authors.initials: AJ
authors.lastname: Palangana