Dynamical reentrance and geometry imposed quantization effects in Nb-AlOx-Nb Josephson junction arrays

In this paper, we report on different phenomena related to the magnetic properties of artificially prepared highly ordered (periodic) two-dimensional Josephson junction arrays (2D-JJA) of both shunted and unshunted Nb-AlOx-Nb tunnel junctions. By employing mutual-inductance measurements and using a high-sensitive bridge, we have thoroughly investigated (both experimentally and theoretically) the temperature and magnetic field dependence of complex AC susceptibility of 2D-JJA. We also demonstrate the use of the scanning SQUID microscope for imaging the local flux distribution within our unshunted arrays

The impact of the Polytechnic Institute of Setubal on the local economy

Este artigo analisa o impacto económico do Instituto Politécnico de Setúbal na região. Utilizando uma abordagem pelo lado da procura, mediu-se o impacto dos gastos dos estudantes, docentes e não docentes, bem como das aquisições de bens e serviços da própria instituição na economia, medindo o impacto no PIB, no emprego, bem como nos gastos totais para a economia. Foi utilizada uma abordagem quantitativa, através da aplicação de questionário a uma amostra aleatória representativa da população alvo. Os resultados revelam um forte impacto económico na região, estimado em 58 milhões de euros (1,77% do PIB dos concelhos de Setúbal e Barreiro) e a sua relevância enquanto empregador (o 2º maior em Setúbal e o 3º no Barreiro). Acresce a forte capacidade de fixar jovens na região para obterem a sua formação superior, com 60% dos estudantes locais a indicarem não ter mudado de residência, mas que iriam estudar para outro local caso o IPS não existisse e de reprodutividade do orçamento de Estado, transformando 1 euro recebido em mais de 3 euros na economia local.info:eu-repo/semantics/publishedVersio

Infrared phonon dynamics of multiferroic BiFeO3 single crystal

We discuss the first infrared reflectivity measurement on a BiFeO3 single crystal between 5 K and room temperature. The 9 predicted ab-plane E phonon modes are fully and unambiguously determined. The frequencies of the 4 A1 c-axis phonons are found. These results settle issues between theory and data on ceramics. Our findings show that the softening of the lowest frequency E mode is responsible for the temperature dependence of the dielectric constant, indicating that the ferroelectric transition in BiFeO3 is soft-mode driven.Comment: 5 pages (figures included

String-like brane splitting in the context of f(T,B)f(T,B) gravity

In this work, the influence of the boundary term $B$ is analyzed in a string-like thick brane scenario in the gravity context $f(T, B)$. For that, three models of $f(T, B)$ are proposed, i.e., $f_1(T, B)=T+k{B}^{n}$, $f_2(T, B)=T+k(-T+B)^{n}$ and $f_3(T, B)=T+k_1T^2+k_2{B}^2$, where $n$, $k$ and $k_{1,2}$ are parameters that control the deviation from the usual teleparallelism. The first relevant result obtained was the appearance of a super-located tower in the core for energy density. Furthermore, the greater the influence of the boundary term, the new maximums and minimums appear in the energy density. All this indicates the emergence of capable structures from split to the brane. The second relevant result was obtained by analyzing the gravitational perturbations, where the effective potential presents the supersymmetric form of quantum mechanics, leading to well-localized massless modes.Comment: 18 pages, 7 captioned figure

Elastic and magnetic effects on the infrared phonon spectra of MnF2

We measured the temperature dependent infrared reflectivity spectra of MnF2 between 4 K and room temperature. We show that the phonon spectrum undergoes a strong renormalization at TN. The ab-initio calculation we performed on this compound accurately predict the magnitude and the direction of the phonon parameters changes across the antiferromagnetic transition, showing that they are mainly induced by the magnetic order. In this material, we found that the dielectric constant is mostly from phonon origin. The large change in the lattice parameters with temperature seen by X-ray diffraction as well as the A2u phonon softening below TN indicate that magnetic order induced distortions in MnF2 are compatible with the ferroelectric instabilities observed in TiO2, FeF2 and other rutile-type fluorides. This study also shows the anomalous temperature evolution of the lower energy Eu mode in the paramagnetic phase, which can be compared to that of the B1g one seen by Raman spectroscopy in many isostructural materials. This was interpreted as being a precursor of a phase transition from rutile to CaCl2 structure which was observed under pressure in ZnF2.Comment: 8 pages, 8 figures, updated version accepted in PR

Exchange coupling inversion in a high-spin organic triradical molecule

The magnetic properties of a nanoscale system are inextricably linked to its local environment. In ad-atoms on surfaces and inorganic layered structures the exchange interactions result from the relative lattice positions, layer thicknesses and other environmental parameters. Here, we report on a sample-dependent sign inversion of the magnetic exchange coupling between the three unpaired spins of an organic triradical molecule embedded in a three-terminal device. This ferro-to-antiferromagnetic transition is due to structural distortions and results in a high-to-low spin ground state change in a molecule traditionally considered to be a robust high-spin quartet. Moreover, the flexibility of the molecule yields an in-situ electric tunability of the exchange coupling via the gate electrode. These findings open a route to the controlled reversal of the magnetic states in organic molecule-based nanodevices by mechanical means, electrical gating or chemical tailoring

Association between calcium intake and body fat among pre-school Portuguese children

Obesity is the condition in which abnormally large body fat mass accumulates and causes a broad range of health problems. Some studies with children have reported an inverse asso ciation between dietary calcium intake and adiposity.info:eu-repo/semantics/publishedVersio