title: Nematic droplets on fibers.
abstract: The emergence of new techniques for the fabrication of nematic droplets with nontrivial topology provides new routes for the assembly of responsive devices. Here we explore some of the properties of nematic droplets on fibers, which constitute the basic units of a type of device that is able to respond to external stimuli, including the detection of gases. We perform a numerical study of spherical nematic droplets on fibers. We analyze the equilibrium textures for homogeneous and hybrid boundary conditions and find that in some cases the nematic avoids the nucleation of topological defects, which would provide a different optical response. We consider in detail a homeotropic nematic droplet wrapped around a fiber with planar anchoring. We investigate the effect of an electric field on the texture of this droplet. In the presence of a dc field, the system undergoes an orientational transition above a given threshold E(c), for which a ring defect is transformed into a figure-eight defect. We also consider ac fields, at high and low frequencies, and find that the textures are similar to those observed for static fields, in contrast with recently reported experiments.
authors.affiliation: Departamento de Física, Faculdade de Ciências, Universidade de Lisboa, Campo Grande, P-1649-003, Portugal.|and Centro de Física Teórica e Computacional, Universidade de Lisboa, Campo Grande, P-1649-003 Lisboa, Portugal.
authors.forename: V M O
authors.initials: VM
authors.lastname: Batista
authors.affiliation: Departamento de Física, Faculdade de Ciências, Universidade de Lisboa, Campo Grande, P-1649-003, Portugal.|and Centro de Física Teórica e Computacional, Universidade de Lisboa, Campo Grande, P-1649-003 Lisboa, Portugal.
authors.forename: N M
authors.initials: NM
authors.lastname: Silvestre
authors.affiliation: Departamento de Física, Faculdade de Ciências, Universidade de Lisboa, Campo Grande, P-1649-003, Portugal.|and Centro de Física Teórica e Computacional, Universidade de Lisboa, Campo Grande, P-1649-003 Lisboa, Portugal.
authors.forename: M M
authors.initials: MM
authors.lastname: Telo da Gama