Fluctuation modes in the twist bend nematic phase of certain liquid crystal mixtures studied by dynamic light scattering

ORAL

Abstract

The ``twist-bend nematic''($N_{TB}$) is a recently discovered phase of liquid crystals. Its ground state features a heliconical molecular arrangement in which the nematic director precesses uniformly about a fixed axis, at a finite angle to this axis. The helicoid has a nanoscale pitch. We present the dynamic light scattering studies in two different mixtures of a dimeric material (M2), which exhibits nematic and $N_{TB}$ phases. In the nematic phase, two fluctuation modes are observed: one is the usual hydrodynamic, uniaxial director mode, while the second is clearly non-hydrodynamic and corresponds to fluctuations of biaxial order. The non-hydrodynamic mode is also observed in the $N_{TB}$ phase, with a significantly higher and strongly temperature-dependent relaxation rate. Scattering from the twist-bend director mode disappears in the $N_{TB}$ phase, while splay fluctuations still contribute. We discuss our results in terms of a theoretical model based on a combination of two elements: (1)a coarse-grained elastic free energy (in which the $N_{TB}$ is modeled a smectic-like, pseudo-layered structure) and (2)a recent theory [1] describing local polar order in the $N_{TB}$ phase.\\[4pt] [1] Phys.Rev.E 87,052503(2013)

–

Authors

  • Zeinab Parsouzi A.Sh

    Kent State University

  • Frazier Baker

    Youngstown State University, Kent State University, Liquid Crystal Institute, Kent State University, Department of Biological Sciences, Kent State University, Department of Physics, Department of Chemistry and Biochemistry, Kent State University, Stony Brook Univ, Ohio Univ, Institute for Advanced Simulation, Institut fur Kernphysik, and Julich Center, Bowling Green State University, Dept. of Physics, Hiram College, Ohio State Univ - Columbus, Kent State University, Psychology Dept, Cleveland State University, Physics Dept, Cleveland State University, Chemical Physics Interdisciplinary Program and Liquid Crystal Institute, Kent State University, Kent, OH 44242-0001, USA, Univ of Konstanz, Univ College London, NIST, Hiroshima Univ, KIT, Missouri University of Science and Technology, University of California, San Diego, Georgia Institute of Technology, KSU, SKKU, Lock Haven Univ, Massachusetts General Hospital, University of Science and Technology of China, Yale University, Shanghai Institute of Microsystem and Information Technology, CAS, Nanjing University, Liquid Crystal Institute and Chemical Physics Interdisciplinary Program, Kent State University, Kent, OH 44242, USA, Department of Physics, Kent State University, Kent OH 44242, Department of Electro-Optic Engineering Ilse Katz Institute for Nanoscale Science and Technology Ben Gurion University, Beer Sheva 84105, Israel, Ohio University Zanesville

  • Frazier Baker

    Youngstown State University, Kent State University, Liquid Crystal Institute, Kent State University, Department of Biological Sciences, Kent State University, Department of Physics, Department of Chemistry and Biochemistry, Kent State University, Stony Brook Univ, Ohio Univ, Institute for Advanced Simulation, Institut fur Kernphysik, and Julich Center, Bowling Green State University, Dept. of Physics, Hiram College, Ohio State Univ - Columbus, Kent State University, Psychology Dept, Cleveland State University, Physics Dept, Cleveland State University, Chemical Physics Interdisciplinary Program and Liquid Crystal Institute, Kent State University, Kent, OH 44242-0001, USA, Univ of Konstanz, Univ College London, NIST, Hiroshima Univ, KIT, Missouri University of Science and Technology, University of California, San Diego, Georgia Institute of Technology, KSU, SKKU, Lock Haven Univ, Massachusetts General Hospital, University of Science and Technology of China, Yale University, Shanghai Institute of Microsystem and Information Technology, CAS, Nanjing University, Liquid Crystal Institute and Chemical Physics Interdisciplinary Program, Kent State University, Kent, OH 44242, USA, Department of Physics, Kent State University, Kent OH 44242, Department of Electro-Optic Engineering Ilse Katz Institute for Nanoscale Science and Technology Ben Gurion University, Beer Sheva 84105, Israel, Ohio University Zanesville

  • Frazier Baker

    Youngstown State University, Kent State University, Liquid Crystal Institute, Kent State University, Department of Biological Sciences, Kent State University, Department of Physics, Department of Chemistry and Biochemistry, Kent State University, Stony Brook Univ, Ohio Univ, Institute for Advanced Simulation, Institut fur Kernphysik, and Julich Center, Bowling Green State University, Dept. of Physics, Hiram College, Ohio State Univ - Columbus, Kent State University, Psychology Dept, Cleveland State University, Physics Dept, Cleveland State University, Chemical Physics Interdisciplinary Program and Liquid Crystal Institute, Kent State University, Kent, OH 44242-0001, USA, Univ of Konstanz, Univ College London, NIST, Hiroshima Univ, KIT, Missouri University of Science and Technology, University of California, San Diego, Georgia Institute of Technology, KSU, SKKU, Lock Haven Univ, Massachusetts General Hospital, University of Science and Technology of China, Yale University, Shanghai Institute of Microsystem and Information Technology, CAS, Nanjing University, Liquid Crystal Institute and Chemical Physics Interdisciplinary Program, Kent State University, Kent, OH 44242, USA, Department of Physics, Kent State University, Kent OH 44242, Department of Electro-Optic Engineering Ilse Katz Institute for Nanoscale Science and Technology Ben Gurion University, Beer Sheva 84105, Israel, Ohio University Zanesville

  • Frazier Baker

    Youngstown State University, Kent State University, Liquid Crystal Institute, Kent State University, Department of Biological Sciences, Kent State University, Department of Physics, Department of Chemistry and Biochemistry, Kent State University, Stony Brook Univ, Ohio Univ, Institute for Advanced Simulation, Institut fur Kernphysik, and Julich Center, Bowling Green State University, Dept. of Physics, Hiram College, Ohio State Univ - Columbus, Kent State University, Psychology Dept, Cleveland State University, Physics Dept, Cleveland State University, Chemical Physics Interdisciplinary Program and Liquid Crystal Institute, Kent State University, Kent, OH 44242-0001, USA, Univ of Konstanz, Univ College London, NIST, Hiroshima Univ, KIT, Missouri University of Science and Technology, University of California, San Diego, Georgia Institute of Technology, KSU, SKKU, Lock Haven Univ, Massachusetts General Hospital, University of Science and Technology of China, Yale University, Shanghai Institute of Microsystem and Information Technology, CAS, Nanjing University, Liquid Crystal Institute and Chemical Physics Interdisciplinary Program, Kent State University, Kent, OH 44242, USA, Department of Physics, Kent State University, Kent OH 44242, Department of Electro-Optic Engineering Ilse Katz Institute for Nanoscale Science and Technology Ben Gurion University, Beer Sheva 84105, Israel, Ohio University Zanesville

  • Frazier Baker

    Youngstown State University, Kent State University, Liquid Crystal Institute, Kent State University, Department of Biological Sciences, Kent State University, Department of Physics, Department of Chemistry and Biochemistry, Kent State University, Stony Brook Univ, Ohio Univ, Institute for Advanced Simulation, Institut fur Kernphysik, and Julich Center, Bowling Green State University, Dept. of Physics, Hiram College, Ohio State Univ - Columbus, Kent State University, Psychology Dept, Cleveland State University, Physics Dept, Cleveland State University, Chemical Physics Interdisciplinary Program and Liquid Crystal Institute, Kent State University, Kent, OH 44242-0001, USA, Univ of Konstanz, Univ College London, NIST, Hiroshima Univ, KIT, Missouri University of Science and Technology, University of California, San Diego, Georgia Institute of Technology, KSU, SKKU, Lock Haven Univ, Massachusetts General Hospital, University of Science and Technology of China, Yale University, Shanghai Institute of Microsystem and Information Technology, CAS, Nanjing University, Liquid Crystal Institute and Chemical Physics Interdisciplinary Program, Kent State University, Kent, OH 44242, USA, Department of Physics, Kent State University, Kent OH 44242, Department of Electro-Optic Engineering Ilse Katz Institute for Nanoscale Science and Technology Ben Gurion University, Beer Sheva 84105, Israel, Ohio University Zanesville

  • Frazier Baker

    Youngstown State University, Kent State University, Liquid Crystal Institute, Kent State University, Department of Biological Sciences, Kent State University, Department of Physics, Department of Chemistry and Biochemistry, Kent State University, Stony Brook Univ, Ohio Univ, Institute for Advanced Simulation, Institut fur Kernphysik, and Julich Center, Bowling Green State University, Dept. of Physics, Hiram College, Ohio State Univ - Columbus, Kent State University, Psychology Dept, Cleveland State University, Physics Dept, Cleveland State University, Chemical Physics Interdisciplinary Program and Liquid Crystal Institute, Kent State University, Kent, OH 44242-0001, USA, Univ of Konstanz, Univ College London, NIST, Hiroshima Univ, KIT, Missouri University of Science and Technology, University of California, San Diego, Georgia Institute of Technology, KSU, SKKU, Lock Haven Univ, Massachusetts General Hospital, University of Science and Technology of China, Yale University, Shanghai Institute of Microsystem and Information Technology, CAS, Nanjing University, Liquid Crystal Institute and Chemical Physics Interdisciplinary Program, Kent State University, Kent, OH 44242, USA, Department of Physics, Kent State University, Kent OH 44242, Department of Electro-Optic Engineering Ilse Katz Institute for Nanoscale Science and Technology Ben Gurion University, Beer Sheva 84105, Israel, Ohio University Zanesville