Material Characterisation and Electro-Optical Studies of a Ferroelectric Liquid Crystal

Department of Electronics, Cochin University of Science and Technology

Growth and characterization of perovskite oxide ferroelectric thin films and its applications

Department of Physics, Cochin University of Science and Technology

RF magnetron sputtered perovskite oxide electrodes for Ferroelectric RAM

The main objective of this thesis work is to optimize the growth conditions for obtaining crystalline and conducting Lao.5Sro.5Co03 (LSCO) and Lao.5Sro.5Coo.5.5Nio.5O3 (LSCNO) thin films at low processing temperatures. The films are prepared by radio frequency magnetron sputtering under various deposition conditions. The thin films were used as electrodes for the fabrication of ferroelectric capacitors using BaO.7SrO.3 Ti03 (BST) and PbZro.52 Tio.4803 (PZT). The structural and transport properties of the La1_xSrxCo03 and Lao.5Sro.5Co1_xNix03 are also investigated. The characterization of the bulk and the thin films were performed using different tools. A powder X-ray diffractometer was used to analyze the crystalline nature of the material. The transport properties were investigated by measuring the temperature dependence of resistivity using a four probe technique. The magnetoresistance and thermoelectric power were also used to investigate the transport properties. Atomic force microscope was used to study the surface morphology and thin film roughness. The ferroelectric properties of the capacitors were investigated using RT66A ferroelectric tester.

Evidence for the existence of Sarkovskii ordering in a two-dimensional map

We analyse numerically the bifurcation structure of a two-dimensional noninvertible map and show that different periodic cycles are arranged in it exactly in the same order as in the case of the logistic map. We also show that this map satisfies the general criteria for the existence of Sarkovskii ordering, which supports our numerical result. Incidently, this is the first report of the existence of Sarkovskii ordering in a two-dimensional map.

Multiferroic Behavior of Gd Based Manganite

Here we report the multiferroic nature of charge ordered manganite Gd0.5Sr0.5MnO3 for the first time. The temperature variation of dielectric constant shows broad relaxor type ferroelectric transition at around 210K and magnetization measurements shows weak ferromagnetism at 50K. The dielectric peak is very close to charge ordering temperature which is an evidence of the link between electronic state and increase of dielectric response. Butterfly variation of capacitance with voltage confirms ferroelectric nature of the sample at room temperature