title: Spherical microparticles with Saturn ring defects and their self-assembly across the nematic to smectic-A phase transition.
abstract: We report experimental studies on the Saturn ring defect associated with a spherical microparticle across the nematic (N) to smectic-A (SmA) phase transition. We observe that the director distortion around the microparticle changes rapidly with temperature. The equilibrium interparticle separation and the angle between two quadrupolar particles in the N phase are larger than those of the SmA phase. They are almost independent of the temperature in both phases, except for a discontinuous jump at the transition. We assembled a few particles using a laser tweezer to form a two-dimensional colloidal crystal in the N phase. The lattice structure of the crystal dissolves irreversibly across the N-SmA phase transition. The results on the pretransitional behavior of the defect are supported by the Landau-de Gennes Q-tensor modeling.
authors.affiliation: School of Physics, University of Hyderabad, Hyderabad-500046, India.
authors.forename: K P
authors.initials: KP
authors.lastname: Zuhail
authors.affiliation: Faculty of Mathematics and Physics, University of Ljubljana, Jadranska 19, SI-1000 Ljubljana, Slovenia.
authors.forename: S
authors.initials: S
authors.lastname: Čopar
authors.affiliation: Faculty of Mathematics and Physics, University of Ljubljana, Jadranska 19, SI-1000 Ljubljana, Slovenia.|Condensed Matter Physics Department, Jožef Stefan Institute, Jamova 39, 1000 Ljubljana, Slovenia.
authors.forename: I
authors.initials: I
authors.lastname: Muševič
authors.affiliation: School of Physics, University of Hyderabad, Hyderabad-500046, India.
authors.forename: Surajit
authors.initials: S
authors.lastname: Dhara