High-contrast imaging of 180° ferroelectric domains by optical microscopy using ferroelectric liquid crystals

Abstract

Ferroelectric liquid crystals (FLCs) couple the direction of their spontaneous electric polarization to the direction of tilt of their optic axis. Consequently, reversal of the electric polarization by an electric field gives rise to an immediate and lasting optical response when an appropriately aligned FLC is observed between crossed polarizers, with one field direction yielding a dark image, and the opposite direction yielding a bright image. Here this peculiar electro-optic response is used to image, with high optical contrast, 180° ferroelectric domains in a crystalline substrate of magnesium-doped lithium niobate. The lithium niobate substrate contains a few domains with upwards electric polarization surrounded by regions with downward electric polarization. In contrast to a reference non-chiral liquid crystal that is unable to show ferroelectric behavior due to its too high symmetry, the FLC, which is used as a thin film confined between the lithium niobate substrate and an inert aligning substrate, reveals ferroelectric domains as well as their boundaries, with strong black and white contrast. The results show that FLCs can be used for nondestructive read-out of domains in underlying ferroelectrics, with potential applications in e.g. photonic devices and non-volatile ferroelectric memories.

Polar nematic phases with enantiotropic ferro- and antiferroelectric behaviour

“…1,2 The technological need for enhanced properties in these materials has led to comprehensive scientific research in this field. [3][4][5][6][7] But nowadays, soft ferroelectrics can bring additional advantages by combining ferroelectric properties with fluidity.…”

New Ferroelectric Liquid Crystalline Materials with Properties Suitable for Surface Stabilized and Deformed Helix Effects

“…After the ferroelectricity in liquid crystals was discovered in 1975 [1], many books and articles were written about synthesis, studies and application of new compounds having such properties [2][3][4][5][6][7][8][9][10][11][12]. Since then, many compounds have been synthesized and new materials on their basis were prepared and tested [13][14][15][16][17][18][19][20][21]. FLCs are characterized by fast electro-optical response, low driving voltage and memory effects, which make them suitable candidates for many advanced applications, such as displays, gratings or sensors [22][23][24][25].…”

Self-Assembling Behavior of Smart Nanocomposite System: Ferroelectric Liquid Crystal Confined by Stretched Porous Polyethylene Film

“…Functional composite nanomaterials are widely spread in our everyday life. During the last few years, various composite materials attract substantial attention due to their advanced properties [1][2][3][4][5][6][7][8][9] that are usually inaccessible for the single component substances. According to definition, the composite materials are those made of at least two constituent compounds with significantly different physical and/or chemical properties that, when combined, might produce a smart resulting material with advanced characteristics different from the individual components under condition that individual components remain chemically separate and distinctive within the final composite structure.…”