Riccardo Barberi

Nonlinear-optical and micro-raman diagnostics of thin films and nanostructures of ABO(3) ferroelectrics

Ferroelectric composite two-dimensional ferroelectric/aluminum oxide nanostructures were studied. A porous aluminum oxide matrix was used as a template into which a ferroelectric precursor was introduced, followed by annealing. The prepared nanostructures were studied using optical second harmonic generation and micro-Raman scattering.

Influence of Growth Conditions on the Morphology of Thin Photopolymer Films

Abstract We report some preliminary results on the morphology of thin photopolymer films. They are observed by means of Atomic Force Microscopy. These films are used as anisotropic substrates for the anchoring of liquid crystals. We study the influence of growth conditions, the drying temperature and the drying time, on the obtained thin film topology with the aim to correlate the observed surface structure with the liquid crystals anchoring. It was found that the final film roughness strongly depends on the drying conditions which govern the photopolymer surface mobility.

Surface Induced Effects in Liquid Crystals: A Microscopic Study

Abstract We present a study of the wetting behavior of small drops of cyanobiphenyl on solid surfaces. Macroscopic and microscopic measurements are compared in order to understand the relationship between anchoring and wetting.

Local Piezoelectric Response and Surface Potential of Dielectric and Ferroelectric Langmuir-Blodgett Films Studied by Electrostatic Force Microscopy

A comparative study of ultrathin dielectric (an azo-compound) and ferroelectric (copolymer P(VDF-TrFE)) Langmuir-Blodgett (LB) films has been carried out by Electrostatic Force Microscopy (EFM). Films were poled locally by a strong d.c. field applied between a conductive tip of an Atomic Force Microscope (AFM) and the bottom Al electrode. The electrically poled domain was studied by EFM using a weak a.c. electric field and a lock-in amplifier technique. Two modes, a contact and non-contact ones, allowed for the measurement of field E a in the air gap between the film and the tip and the piezoelectric distortion of the film due to the d.c. field aligned spontaneous polarization. Simultaneously the topographic relief of the same area was imaged. The results confirm unequivocally a possibility to switch ferroelectric LB film locally by an AFM tip.