POLARISABLE MATERIAIS AND FUNCTIONAL NANOSTRUCTURES
For more details about this research see the webpage of IFIMUP or contact prof. Abilio Almeida (amalmeid[AT]fc.up.pt)
Research activity has been focused on the following topics: competitive magnetic/electric interactions, relaxation processes, statics and dynamics in polarizable thin films and heterostructures, magnetoelectric effect, spin-phonon coupling, multifunctionality at nano-scale, specially in electrically driven spintronics. In this scope, several systems have been selected which involve mainly transition metal oxides (TMOs). In these systems as it was reckoned in the past by Landau, the concept of symmetry breaking is a fundamental issue for understanding some of the more distinctive physical properties of TMOs: ferroelectricity, ferromagnetism, and superconductivity can be readily explained by spacial inversion, time reversal and Gauge symmetry breaking, respectively. These phenomena emerge from the collective behaviour of electrons, by the interplay among electronic degrees of freedom. In this regard, both electrically and magnetically polarisable materials, or of both kinds have been investigated. Special attention has been paid to those, which exhibit spin-phonon coupling and/or magnetoelectric effect. Moreover, micro- and nanostructured composites were produced based on oxides in order to profit from their different properties, which could be enhanced through the balance of crossed electric/strain coupling mechanisms. Another main objective of the group in addressed to medical applications: cancer detection using non-evasive like Raman and THz spectroscopies, in order to exclude chirurgical intervention to obtain information about the sort of lesion. A new objective has been to establish the basis for a consistent group of collaborators, in both the scientific and educational research fields of interactive materials and experiments, as tools for a better understanding and spreading of fundamental knowledge in Science and their applications. Publishing of works in this field is also aimed. Experimental studies have been performed on samples having diverse forms and shapes, ranging from monocrystals, bulk ceramics, ultra-thin films and multilayers, to nanostructures. In order to study some of their properties medium high magnetic dc fields (up to 7 T), and extremely high pressures (60 Gpa) have been used, whenever applicable. Moreover, dimension-size effects were also envisaged, in the materials under investigation. A set of available techniques in place or from collaboration with other research groups has been used.
Dynamic and structural properties of orthorhombic rare-earth manganites under high pressure, D. A. Mota, A. Almeida, V. H. Rodrigues, M. M. R. Costa, P. Tavares, P. Bouvier, M. Guennou, J. Kreisel, J. Agostinho Moreira, Phys Rev B, 90, 054104 (2014). |www|
R. Rodrigues, P. Simeão Carvalho, Using computational simulations to confront students' mental models, Phys. Educ., 49, 195-200 (2014). |www|
Local Bias Induced Ferroelectricity in Manganites With Competing Charge and Orbital Order States, Fábio G. N. Figueiras, Igor K. Bdikin, Vitor B. S. Amaral, Andrei L. Kholkin, Phys. Chem. Chem. Phys., 16, 4977-4981 (2014). |www|