arXiv subjects

Gu Yan

Publications and source records attributed to Gu Yan.

4 recordsLinked to original sources

arXiv1997

Chirality in Liquid Crystals: from Microscopic Origins to Macroscopic Structure

Molecular chirality leads to a wonderful variety of equilibrium structures, from the simple cholesteric phase to the twist-grain-boundary phases, and it is responsible for interesting and technologically important materials like ferroelectric liquid crystals. This paper will review some recent advances in our understanding of the connection between the chiral geometry of individual molecules and the important phenomenological parameters that determine macroscopic chiral structure. It will then consider chiral structure in columnar systems and propose a new equilibrium phase consisting of a regular lattice of twisted ropes.

cond-mat.soft↗

arXiv1996

Chiral Discotic Columnar Phases in Liquid Crystals

We introduce a model to describe columnar phases of chiral discotic liquid phases in which the normals to disc-like molecules are constrained to lie parallel to columnar axes. The model includes separate chiral interactions favoring, respectively, relative twist of chiral molecules along the axes of the columns and twist of the two-dimensional columnar lattice. It also includes a coupling between the lattice and the orientation of the discotic molecules. We discuss the instability of the aligned hexagonal lattice phase to the formation of a soliton lattice in which molecules twist within their columns without affecting the lattice and to the formation of a moiré phase consisting of a periodic array of twist grain boundaries perpendicular to the columns.

cond-mat.soft↗

arXiv1995

Temporal Fluctuations in Nematic Liquid Crystals

We use a set of simplified non-linear Langevin equations to study the hydrodynamic excitations in a nematic liquid crystal. We calculate the one-loop self-energy corrections in the long wavelength limit.

cond-mat↗

arXiv1994

Non-Fermi Liquid Behavior in 3+1 Dimensions with PT Invariant Gauge Field: An Renormalization Group Approach

We introduce a Hamiltonian coupled between a normal Fermi surface and a polarized Maxwell type gauge field.We adopt a {\it calibrated scaling } approach in order to be consistent with the results obtained at $2+1$ dimensions as well as the Weinberg's theo rem. Renormalization group equations are calculated by using a dimension regulator. It turns out that the gauge interaction is controlled by a non-trivial fixed point. The two-point Green's function can thus be calculated accurately in the low temperature limit and possesses a non-quasi particle pole which signals the break down of the Landau Fermi liquid theory. In addition,we show that the anomalous dimension of fermion field is in general gauge dependent. But it will survive under generic gauge choice due to the renormalization of the gauge fixing parameter.

cond-mat↗