Condensed Matter Theory

Abstract:

We construct a family of BCS paired composite-fermion wave functions that generalize but remain in the same topological phase as the Moore-Read Pfaffian state for the half-filled Landau level. It is shown that for a wide range of experimentally relevant interelectron interactions, the ground state can be very accurately represented in this form. © 2008 The American Physical Society.

Abstract:

Active liquid crystals or active gels are soft materials which can be physically realised, e.g. by preparing a solution of cytoskeletal filaments interacting with molecular motors. We study the hydrodynamics of an active liquid crystal in a slab-like geometry with various boundary conditions, by solving numerically its equations of motion via lattice Boltzmann simulations. In all cases we find that active liquid crystals can sustain spontaneous flow in steady state contrarily to their passive counterparts, and in agreement with recent theoretical predictions. We further find that conflicting anchoring conditions at the boundaries lead to spontaneous flow for any non-zero value of the 'activity' parameter, while with unfrustrated anchoring at all boundaries spontaneous flow only occurs when the activity exceeds a critical threshold. We finally discuss the dynamic pathway leading to steady state in a few selected cases. (c) 2007 Elsevier B.V. All fights reserved.