Browsing CAP - Indexed Articles in Conferences by Author "Abilio Almeida"
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ItemCHARACTERIZATION OF RF SPUTTERED MTaO3 (M=Li, Na, K) THIN FILMS( 2012) Abilio Almeida ; Yonny Romaguera ; Daniel Alfredo Mota ; Alex Tkach ; Javier Cruz ; Joaquim A. MoreiraAmong the family of transition metal oxides, the MTaO3 (M=Li, Na, K) compounds have attracted a great interest from researchers from a fundamental and technological point of view. LiTaO3 is isomorph to LiNbO3 and both exhibit ferroelectricity at room temperature. Owing to the polar characteristics, these materials can be used in transducers, sensors, and optical applications. Contrarily, NaTaO3 and KTaO3, though possessing polar soft modes, do not exhibit ferroelectricity at finite temperatures. All these materials possess a highly polarizable lattice, yielding their properties very sensitive to defects, impurities, elastic, and applied electric fields. These factors can easily induce ferroelectricity and intermediate glass- or relaxor-like states. Though a relative high number of works has been published in bulk MTaO3 systems, their study in thin film form is still scarce and their behaviour is yet not fully understood. In this work MTaO3 thin films were prepared by radio frequency...
ItemDIMENSIONAL EFFECTS ON THE STRUCTURE AND MAGNETIC PROPERTIES OF GdMnO3 FILMS( 2012) Joaquim A. Moreira ; Yonny Romaguera ; Javier Cruz ; Abilio AlmeidaRecent advances in thin films growth techniques have enabled to prepare a large variety of heterostructures consisting of materials with different crystal structures and physical properties. In particular, the research on the application of magnetoelectric materials as barriers and interfaces for spintronic has known a very large increase. Moreover, the low dimensionality and size required for such devices can yield drastic changes onto both structure and physical properties of the bulk materials, largely due to substrate-induced structural deformations. This work was focused in the study of high quality GdMnO3 thin films, obtained by a chemical solution method onto oriented Pt substrates. Alterations regarding to lattice dynamic and magnetic response of the films compared to both ceramics and single crystals ascertained through Raman and magnetic studies show that the behaviour of the as-prepared films can be understood by assuming a continuously changing of the stress state in the fi
ItemSTRUCTURAL AND MAGNETIC PROPERTIES OF YMNO3 THIN FILM PREPARED BY CHEMICAL SOLUTION METHOD( 2012) Yonny Romaguera ; Javier Cruz ; Joaquim A. Moreira ; Abilio AlmeidaThe coupling between the magnetic and electric dipolar orders, which enables to control the electric polarization with magnetic field and vice-versa, has opened new trends in multifunctional device design. The extensive study of the physical properties of magnetoelectric or multiferroic material has been carried out mainly in both single crystals and ceramic samples. However, for technological applications, thin films and nano-structured systems are much more attractive. Magnetoelectric or multiferroic thin films have been processed using a variety of growth techniques, including r.f. sputtering, pulsed laser ablation, molecular bean epitaxy and chemical solution deposition. The latter method is a quite promising one, as it provides higher composition control, lower deposition temperatures, shorter fabrication time and relative lower cost. In this work, we report the preparation of YMnO3 thin films by chemical solution deposition onto platinized silicon substrates. In order to charact