Angular dependent vortex dynamics in superconductors with columnar defects

We explore in detail the angular dependent vortex dynamics in type II superconductors with aligned columnar defects introduced by irradiation with very energetic heavy-ions. We use dc magnetization measurements deep in the vortex solid phase, and ac susceptibility near the solid-liquid transition. We show that aligned columnar defects are an excellent tool to test models for vortex dynamics, particularly if they are tilted with respect to the crystallographic axes, so their effects can be easily distinguished from those arising from mass anisotropy, sample geometry, twin boundaries and intrinsic pinning. This allows us, for instance, to use the uniaxial pinning of the columnar defects as a probe to determine the orientation of the vortices inside a bulk material, which in general is different from the orientation of the applied fields. In some aspects we have found an excellent agreement with the theoretical expectations of the Bose-glass model. The field dependence of the lock-in angle follows remarkably well the 1/H prediction over the whole temperature range of our measurements. In turn, the temperature dependence of the lock-in angle gives strong support to the concept of an effective pinning energy dominated by the entropic smearing effect. On the other hand, both our ac and dc results show that columnar defects produce effective pinning over a wide angular range, and that correlated pinning dominates the scenario for all field orientations. One consequence of this is the existence of a rich variety of vortex staircases.Comment: to be published in International Book series "Studies of High Temperature Superconductors", edited by Anant Narlikar, Nova Science Publishers, New York, Vol 49/50, (2003

Um iluminista na aldeia dos Tupinambás

O artigo visa compreender o processo de constituição do saber sobre a história da cidade do Rio de Janeiro, levando em consideração não apenas as inclinações políticas de Delgado de Caralho e suas relações com eminentes figuras da cidade, mas também as estratégias narrativas do autor. Não buscamos, assim, integrar o pensador em uma categoria mais ampla de intelectuais no pensamento social brasileiro, nem tampouco tecer considerações sobre o período histórico em que o livro foi publicado. Ainda que estas questões não sejam negligenciadas, o artigo aborda a maneira pela qual o autor escreve a história da cidade, enfocando não só aspectos teóricos e metodológicos, mas também sua apropriação do saber histórico e geográfico de sua época sobre o lugar e o tempo a fim de se inserir na vida social, política e cultural da cidade do Rio de Janeiro. O artigo visa compreender como se construiu uma versão da história do Rio que se confundia com os ícones da cultura moderna da década de 1920. A formação intelectual de Delgado de Carvalho, os objetivos do livro, a concepção de como fazer história e geografia e a relação com figuras políticas do período ajudam a compreender a interpretação do autor sobre a história de um lugar: a cidade do Rio de Janeiro.L`objectif de l`article est de comprendre le processus de constitution du savoir sur l`histoire de la ville de Rio de Janeiro, tenant compte, autre que des inclinaisons politiques de Delgado de Carvalho et ses relations avec des hauts responsables de la ville, des stratégies narratives de l`auteur. Nous ne cherchons pas, ainsi, intégrer le penseur dans une catégorie plus étendue d`intellectuels dans la pansée sociale brésilienne, pas plus que tisser des considérations sur la période historique dans laquelle le livre a été publié. Même si ces questions ne sont pas négligées, l`article soulève la manière par laquelle l`auteur écris l`histoire de la ville, soulevant pas seulement des aspects théoriques et méthodologiques, mais aussi son appropriation du savoir historique et géographique de l`époque sur le lieu et le temps, afin de s`insérer dans la vie sociale, politique et culturelle de la ville de Rio de Janeiro. L`article a pour but de comprendre comment s`est construite une version de l`histoire de Rio qui s`est confondue avec les icones de la culture moderne des années 20. La formation intellectuelle de Delgado de Carvalho, les objectifs du livre, la conception de comment faire histoire et géographie et la relation avec des personnages politiques de la période ont aidé a comprendre l`interprétation de l`auteur sur l`histoire d`un lieu: la ville de Rio de Janeiro.Este artículo intenta comprender la constitución del conocimiento histórico sobre la ciudad de Río de Janeiro, teniendo en cuenta no sólo la inclinación política de Delgado de Carvalho y sus relaciones con eminentes figuras de la ciudad, sino también las estrategias narrativas del autor. De esta manera, en lugar de situar el investigador en una categoría de intelectuales del pensamiento social brasileño y poner en relieve aspectos del período histórico en que se publicó el libro, resaltamos la manera en que Delgado de Carvalho escribe la historia de la ciudad, considerando no sólo sus aportes teóricos y metodológicos sino también su apropiación del saber histórico y geográfico acumulado sobre el Río de Janeiro, logrando insertarse en la vida social, política y cultural de la ciudad. El artículo pretende comprender cómo se construyó una versión de la historia de Río que se confundía con los iconos de la cultura moderna de la década de 1920. La formación intelectual de Delgado de Carvalho, los objetivos del libro, la concepción de cómo hacer historia y geografía y la relación del autor con las figuras políticas del período ayudan a comprender su interpretación sobre la historia de un lugar: la ciudad de Río de Janeiro.The article aims to understand the process of knowledge formation on the history of the city of Rio de Janeiro. We do not take into account only the political inclinations of Delgado de Caralho and his relations with eminent city figures, but also the narrative strategies of the author. We do not seek to integrate the thinker into a broader category of intellectuals in Brazilian social thought, nor to consider considerations about the historical period in which the book was published. Even if these issues are considered, the article discusses the way in which the author writes the history of the city, focusing not only on theoretical and methodological aspects, but also his appropriation of the historical and geographic knowledge of his time about the place and the time to be inserted in the social, political and cultural life of the city of Rio de Janeiro. The article aims to understand how a version of Rio de Janeiro’s history was built in parallel with the icons of the modern culture of the 1920’s. The intellectual formation of Delgado de Carvalho, the objectives of the book, the conception of how to make history and geography and the relationship with political figures of the period help to understand the author's interpretation of the history of a place: the city of Rio de Janeiro

Políticas culturais e patrimônio: uma análise sobre a gestão do Plano Municipal de Cultura de Itabirito – MG

The article analyzes the Municipal Culture Plan (MCP) of the city of Itabirito, in Minas Gerais, while supporting to the development of public policies in the cultural sector in the last years (2016-2020). As a methodological development, it is adressed how the MCPs act in the strenghtening of public policies to the development of the culture, as well as in the preservation of the Cultural Heritage. It is understood that the culture plans are the “gears” that make the cultural system work, without which this engine doesn’t work, doesn’t rotate and the system doesn’t “run”. It is previously concluded that Itabirito’s MCP is a participatory, technical and planned document, that seeks to align the population’s concerns with the interests and possibilities of the local Government.O artigo analisa o Plano Municipal de Cultura (PMC) do município de Itabirito, em Minas Gerais, enquanto coadjuvante para o desenvolvimento de políticas públicas no setor cultural nos últimos anos (2016-2020). Como desenvolvimento metodológico, é abordado como os Planos Municipais de Cultura atuam no fortalecimento das políticas públicas para o desenvolvimento da cultura, assim como na preservação do Patrimônio Cultural. Entende-se que os planos de cultura são as “engrenagens” que fazem funcionar o sistema cultural, sem os quais esse motor não funciona, não gira e o sistema não “anda”. Conclui-se que o Plano Municipal de Cultura de Itabirito é um documento participativo, técnico e planejado que busca alinhar os anseios da população aos interesses e possibilidades do Poder Público local

Instrumentalización turística del paisaje cultural. El caso de Santo Stefano di Sessanio, Italia

This article aims at to analyze the process of resignification of the cultural landscape of the Italian municipality of Santo Stefano di Sessanio, between 1999 and 2014. After a background of both economic and demographic decline started at the late of XIX century, the place has been experimenting since the beginning of the current century a set of touristic  interventions which deal for evoking the historicity of  local landscape from its morphological aspects. Among other things, this has entailed in the restoration of a group of local old buildings in order to transform them into part of a network of diffused hotels. The article is structured around sources which came from both public institutions and private groups that have intervened in the local territory. The research evinces the importance that tourism activity has been had in the municipality after the territorial abandonment context.Este artículo analiza el proceso de implementación de un proyecto turístico en la comuna italiana de Santo Stefano di Sessanio, entre 1999 y 2014. Tras un contexto de estancamiento económico y declive demográfico emergidos a finales del siglo XIX, la localidad ha venido experimentando desde principios del siglo XX un conjunto de intervenciones turísticas que buscan evocar la historicidad local a partir de la instrumentalización de los aspectos morfológicos de su paisaje cultural. Eso ha culminado en el restauro de un conjunto de edificios con el fin de transformarles en una red de albergues difusos. El artículo está armado tras  un recorrido teórico que incluye análisis de materiales brindados por instituciones locales y grupos privados que han intervenido en dicha comuna. De este modo, el trabajo evidencia la importancia que el turismo ha tenido en el municipio de Santo Stefano di Sessanio post el contexto de abandono territorial

Vortex phases and glassy dynamics in the highly anisotropic superconductor HgBa2_{2}CuO4+δ_{4+δ}

We present an extensive study of vortex dynamics in a high-quality single crystal of HgBa$_{2}$CuO$_{4+δ}$, a highly anisotropic superconductor that is a model system for studying the effects of anisotropy. From magnetization M measurements over a wide range of temperatures T and fields H, we construct a detailed vortex phase diagram. We find that the temperature-dependent vortex penetration field H$_{p}$(T), second magnetization peak H$_{smp}$(T), and irreversibility field H$_{irr}$(T) all decay exponentially at low temperatures and exhibit an abrupt change in behavior at high temperatures T/Tc >~ 0.5. By measuring the rates of thermally activated vortex motion (creep) S(T, H) = |dlnM(T, H)/dlnt|, we reveal glassy behavior involving collective creep of bundles of 2D pancake vortices as well as temperature- and time-tuned crossovers from elastic (collective) dynamics to plastic flow. Based on the creep results, we show that the second magnetization peak coincides with the elastic-to-plastic crossover at low T, yet the mechanism changes at higher temperatures

Designing high-performance superconductors with nanoparticle inclusions: Comparisons to strong pinning theory

One of the most promising routes for achieving high critical currents in superconductors is to incorporate dispersed, non-superconducting nanoparticles to control the dissipative motion of vortices. However, these inclusions reduce the overall superconducting volume and can strain the interlaying superconducting matrix, which can detrimentally reduce T$_{c}$. Consequently, an optimal balance must be achieved between the nanoparticle density n$_{p}$ and size d. Determining this balance requires garnering a better understanding of vortex–nanoparticle interactions, described by strong pinning theory. Here, we map the dependence of the critical current on nanoparticle size and density in (Y$_{0.77}$, Gd$_{0.23}$)Ba$_{2}$Cu$_{3}$O$_{7−δ}$ films in magnetic fields of up to 35 T and compare the trends to recent results from time-dependent Ginzburg–Landau simulations. We identify consistency between the field-dependent critical current J$_{c}$ (B) and expectations from strong pinning theory. Specifically, we find that J$_{c}$ ∝ B$^{−α }$, where α decreases from 0.66 to 0.2 with increasing density of nanoparticles and increases roughly linearly with nanoparticle size d/ξ (normalized to the coherence length). At high fields, the critical current decays faster (∼B$^{Z-1}$), suggesting that each nanoparticle has captured a vortex. When nanoparticles capture more than one vortex, a small, high-field peak is expected in Jc(B). Due to a spread in defect sizes, this novel peak effect remains unresolved here. Finally, we reveal that the dependence of the vortex creep rate S on nanoparticle size and density roughly mirrors that of α, and we compare our results to low-T nonlinearities in S(T) that are predicted by strong pinning theory