Verifying XY-Model Predictions for Topological Defects in Films of Smectic Liquid Crystals

POSTER

Abstract

We describe experiments exploring the applicability of the XY model to defect-rich smectic C liquid crystal films. Topological defects in the orientation field are created by rapidly deflating a hemispherical `bubble’ of a molecularly thin film, resulting in a flat film with a high density of defects. The subsequent pair-wise annihilation of these defects is captured with sub-millisecond resolution using high-speed, polarized light video microscopy. The simplest theoretical description of the orientation field, the XY model, makes specific predictions about the annihilation dynamics, predicting sub-logarithmic scaling of the number of defects present at short times and logarithmic scaling at longer times. Progress towards verifying the applicability of the XY model to these systems at early times has been stymied by experimentally difficulties in tracking the defects. Through improvements in illumination and by leveraging recent advances in machine-learning, we can now identify and track individual defects at early times, allowing us to confirm the predictions of the XY model.

**Work supported by NASA Grant No. NNX-13AQ81G and NAG No. NNX17AC74G and by the Soft Materials Research Center under NSF MRSEC Grant No. DMR-1420736.

Presenters

  • Cheol Park

    • Physics and Soft Materials Research Center, University of Colorado Boulder
    • Physics and Soft Materials Research Center, University of Colorado

Authors

  • Cheol Park

    • Physics and Soft Materials Research Center, University of Colorado Boulder
    • Physics and Soft Materials Research Center, University of Colorado

  • Adam Green

    • Physics and Soft Materials Research Center, University of Colorado Boulder

  • Stian Howard

    • Physics and Soft Materials Research Center, University of Colorado Boulder

  • Eric Minor

    • Physics and Soft Materials Research Center, University of Colorado Boulder

  • Joseph E MacLennan

    • Physics and Soft Materials Research Center, University of Colorado Boulder
    • University of Colorado, Boulder
    • Department of Physics, University of Colorado, Boulder
    • Physics and Soft Materials Research Center, University of Colorado

  • Matthew Glaser

    • Physics and Soft Materials Research Center, University of Colorado Boulder
    • University of Colorado, Boulder
    • Department of Physics, University of Colorado, Boulder
    • Institute of Solid State Physics, Otto von Guericke University

  • Noel Anthony Clark

    • Physics and Soft Materials Research Center, University of Colorado Boulder
    • University of Colorado, Boulder
    • Department of Physics, University of Colorado, Boulder
    • Physics and Soft Materials Research Center, University of Colorado