Multigap ferroelectric and antiferroelectric smectic phases
Groupe Structure de la Matière sous Conditions
SNBL/ESRF - 38043 Grenoble, France
2 LPMC, Université de Picardie - 80039 Amiens, France
Accepted: 25 January 2001
We present a phenomenological model describing spatial modulations of the (anti)polarization in chiral tilted smectic phases. The helical instability of the polarization field direction combines with a second instability associated with the polarization amplitude. We predict new structures exhibiting a mismatch between the helix pitch and the amplitude modulation length. These incommensurate phases display extraordinary optical properties, resulting from a multi-gap band structure in their electromagnetic dispersion relations. Such structures could be used as natural photonic crystals.
PACS: 61.30.Cz – Molecular and microscopic models and theories of liquid crystal structure / 61.44.Fw – Incommensurate crystals / 61.30.Gd – Orientational order of liquid crystals; electric and magnetic field effects on order
© EDP Sciences, 2001