Beyond power laws: Universality in the average avalanche shape

We report the measurement of multivariable scaling functions for the temporal average shape of Barkhausen noise avalanches, and show that they are consistent with the predictions of simple mean-field theories. We bypass the confounding factors of time-retarded interactions (eddy currents) by measuring thin permal- loy films, and bypass thresholding effects and amplifier distortions by applying Wiener deconvolution. We find experimental shapes that are approximately symmetric, and track the evolution of the scaling function. We solve a mean- field theory for the magnetization dynamics and calculate the form of the scaling function in the presence of a demagnetizing field and a finite field ramp-rate, yielding quantitative agreement with the experiment.Comment: 13 pages, 14 figure

Playing with universality classes of Barkhausen avalanches

Many systems crackle, from earthquakes and financial market to Barkhausen effect in ferromagnetic materials. Despite the diversity in essence, the noise emitted in these dynamical systems consists of avalanche-like events with broad range of sizes and durations, characterized by power-law avalanche distributions and typical average avalanche shape that are signatures dependent on the universality class of the underlying dynamics. Here we focus on the crackling noise in ferromagnets and scrutinize the traditional statistics of Barkhausen avalanches in polycrystalline and amorphous ferromagnetic films having different thicknesses. We show how scaling exponents and average shape of the avalanches evolve with the structural character of the materials and film thickness. We find quantitative agreement between experiment and theoretical predictions of models for the magnetic domain wall dynamics, and then elucidate the universality classes of Barkhausen avalanches in ferromagnetic films. Thereby, we observe for the first time the dimensional crossover in the domain wall dynamics, and the outcomes of the interplay between system dimensionality and range of interactions governing the domain wall dynamics on Barkhausen avalanches.Comment: 6 figures, 2 table

Directional field-dependence of magnetoimpedance effect on integrated YIG/Pt-stripline system

We investigated the magnetization dynamics through the magnetoimpedance effect in an integrated YIG/Pt-stripline system in the frequency range of 0.5 up to 2.0 GHz. Specifically, we explore the dependence of the dynamic magnetic behavior on the field orientation by analyzing beyond the traditional longitudinal magnetoimpedance effect of the transverse and perpendicular setups. We disclose here the strong dependence of the effective damping parameter on the field orientation, as well as verification of the very-low damping parameter values for the longitudinal and transverse configurations. We find considerable sensitivity results, bringing to light the facilities to integrate ferrimagnetic insulators in current and future technological applications.This research was funded by CNPq grand numbers 304943/2020-7 and 407385/2018-5, Capes grand number 88887.573100/2020-00 and FCT grant number CTTI-31/18-CF(2)

High performance of metallic thin films for resistance temperature devices with antimicrobial properties

Titanium-copper alloy films with stoichiometry given by Ti1−xCux were produced by magnetron co-sputtering technique and analyzed in order to explore the suitability of the films to be applied as resistive temperature sensors with antimicrobial properties. For that, the copper (Cu) amount in the films was varied by applying different DC currents to the source during the deposition in order to change the Cu concentration. As a result, the samples showed excellent thermoresistivity linearity and stability for temperatures in the range between room temperature to 110 °C. The sample concentration of Ti0.70Cu0.30 has better characteristics to act as RTD, especially the αTCR of 1990 ×10−6°C−1. The antimicrobial properties of the Ti1−xCux films were analyzed by exposing the films to the bacterias S. aureus and E. coli, and comparing them with bare Ti and Cu films that underwent the same protocol. The Ti1−xCux thin films showed bactericidal effects, by log10 reduction for both bacteria, irrespective of the Cu concentrations. As a test of concept, the selected sample was subjected to 160 h reacting to variations in ambient temperature, presenting results similar to a commercial temperature sensor. Therefore, these Ti1−xCux thin films become excellent antimicrobial candidates to act as temperature sensors in advanced coating systems.This work was supported by FCT-UIDB/04650/2020. A.L.R.S. thanks CAPES (88887.572905 /2020-00) and CNPq. M.A.C. thanks CAPES (8887.573100/2020-00) and CNPq. A.F. thanks the FCT (CTTI-31/18-C.F. (2) junior researcher contract)

Anomalous Nernst Effect in flexible co-based amorphous ribbons

Fe3Co67Cr3Si15B12 ribbons with a high degree of flexibility and excellent corrosion stability were produced by rapid quenching technique. Their structural, magnetic, and thermomagnetic (Anomalous Nernst Effect) properties were studied both in an as-quenched (NR) state and after stress annealing during 1 h at the temperature of 350 °C and a specific load of 230 MPa (AR). X-ray diffraction was used to verify the structural characteristics of our ribbons. Static magnetic properties were explored by inductive technique and vibrating sample magnetometry. The thermomagnetic curves investigated through the Anomalous Nernst Effect are consistent with the obtained magnetization results, presenting a linear response in the thermomagnetic signal, an interesting feature for sensor applications. Additionally, Anomalous Nernst Effect coefficient SANE values of 2.66μV/K and 1.93μV/K were estimated for the as-quenched and annealed ribbons, respectively. The interplay of the low magnetostrictive properties, soft magnetic behavior, linearity of the thermomagnetic response, and flexibility of these ribbons place them as promising systems to probe curved surfaces and propose multifunctional devices, including magnetic field-specialized sensors.M.A.C. thanks CAPES (8887.573100/2020-00) and CNPq. A.F. thanks the FCT (CTTI-31/18- C.F. (2) junior researcher contract). G.V.K was supported in the frame of the Priority-2030 Program of Ural Federal University

Mapeamento do COVID-19 na macrorregião de saúde da foz do rio Itajaí

In March 2020, the first case of severe acute respiratory syndrome corona virus 2 (SARS - CoV-2), known as Covid-19, was registered. Considering the fast dissemination, cases and deaths increased in several countries, the World Health Organization (WHO) declared that to control the virus proliferation, it is necessary to implement restrictive measures to be followed individual, environmental and for Community scope. Knowing the facts, this article aimed to map the number of cases and deaths of Covid-19 in the municipalities of the macro-region at Foz do Rio Itajaí, from March 18 to May 18 of 2020 and notify them to municipal power responsible for restrictive measures for the 11 municipalities that belongs the area from the epidemiological reports issued by SES / SC and to identify the expansion of contamination through digital mapping. As a result, it was found that at the end of the analysis period, the 11 municipalities that contemplate the area registered at least one case of Covid-19. It was identified also that the municipalities had an independent dissemination behavior, as well as the restrictive decree regulation, each municipality having different measures on different periods. Realized that restrictive measures of individual, environmental and community scope, according to their content, can reduce the contagion of the disease for longer and have direct impacts on the spread and control of the virus, as the municipalities that issued the largest number of decree in the period, and less cases confirmed.En marzo de 2020, se registró el primer  Covid-19. Teniendo en cuenta la rápida difusión, los casos y las muertes aumentaron en varios países, la Organización Mundial de la Salud  declaró que para controlar la proliferación del virus, es necesario implementar medidas restrictivas que se sigan de forma individual, ambiental y de alcance comunitario. Conociendo los hechos, este artículo tuvo como objetivo mapear el número de casos y muertes de Covid-19 en los municipios de la macro-región de Foz do Rio Itajaí, del 18 de marzo al 18 de mayo de 2020 y notificarlos al poder municipal responsable de la restricción medidas para los 11 municipios que pertenecen al área a partir de los informes epidemiológicos emitidos por SES / SC e identificar la expansión de la contaminación a través del mapeo digital. Como resultado, se encontró que al final del período de análisis, los 11 municipios que contemplan el área registraron al menos un caso de Covid-19. También se identificó que los municipios tenían un comportamiento de difusión independiente, así como la regulación restrictiva de los decretos, cada municipio tenía diferentes medidas en diferentes períodos. Se dio cuenta de que las medidas restrictivas de alcance individual, ambiental y comunitario, de acuerdo con su contenido, pueden reducir el contagio de la enfermedad por más tiempo y tener un impacto directo en la propagación y el control del virus, ya que los municipios que emitieron el mayor número de decretos en el período, y menos casos confirmados.Em março de 2020, foi registrado em Santa Catarina o primeiro caso de síndrome respiratória aguda grave corona vírus 2 (SARS – CoV-2), conhecida como COVID-19. Tendo em vista o comportamento de disseminação gradativa e rápida, com o surgimento de casos e óbitos em diversos países, a Organização Mundial da Saúde (OMS) declarou que para controlar a proliferação do vírus, é necessário aplicar medidas restritivas de alcance individual, ambiental e comunitário. Considerando o exposto, o presente artigo teve como objetivo mapear o número de casos e óbitos da COVID-19 nos municípios da macrorregião da foz do Rio Itajaí, no período de 18 de março à 18 de maio de 2020 e relacioná-los com as medidas restritivas municipais dos 11 municípios que integram a região a partir dos boletins epidemiológicos emitidos pela SES/SC e identificar a expansão da contaminação por meio do mapeamento digital. Como resultado, constatou-se que ao final do período de análise, os 11 municípios que contemplam a região registraram ao menos um caso da COVID-19. Foi identificado que os municípios tiveram um comportamento de disseminação de forma independente, assim como os decretos de normas restritivas, tendo cada município diferentes medidas em datas distintas. Percebe-se que as medidas restritivas de alcance individual, ambiental e comunitário, de acordo com seu conteúdo, podem restringir o contágio da doença por mais tempo e ter impactos direto na disseminação e controle da doença, sendo que os municípios que emitiram o maior número de decretos no período, tiveram menores números de casos confirmados

Magnetic response dependence of ZnO based thin films on Ag doping and processing architecture

Multifunctional and multiresponsive thin films are playing an increasing role in modern technology. This work reports a study on the magnetic properties of ZnO and Ag-doped ZnO semiconducting films prepared with a zigzag-like columnar architecture and their correlation with the processing conditions. The films were grown through Glancing Angle Deposition (GLAD) co-sputtering technique to improve the induced ferromagnetism at room temperature. Structural and morphological characterizations have been performed and correlated with the paramagnetic resonance measurements, which demonstrate the existence of vacancies in both as-cast and annealed films. The magnetic measurements reveal changes in the magnetic order of both ZnO and Ag-doped ZnO films with increasing temperature, showing an evolution from a paramagnetic (at low temperature) to a diamagnetic behavior (at room temperature). Further, the room temperature magnetic properties indicate a ferromagnetic order even for the un-doped ZnO film. The results open new perspectives for the development of multifunctional ZnO semiconductors, the GLAD co-sputtering technique enables the control of the magnetic response, even in the un-doped semiconductor materials.The Brazilian agencies CNPq, CAPES partially supports the research. From Portugal side, this work was supported by the Portuguese Foundation for Science and Technology (FCT) in the framework of the Strategic Funding UID/FIS/04650/2020 and the junior research contract (A.F.). Financial support from the Basque Government Industry Department under the ELKARTEK. HAZITEK and PIBA programs is also acknowledged

Improving the room-temperature ferromagnetism in ZnO and low-doped ZnO:Ag films using GLAD sputtering

ZnO and doped ZnO films with non-ferromagnetic metal have been widely used as biosensor elements. In these studies, the electrochemical measurements are explored, though the electrical impedance of the system. In this sense, the ferromagnetic properties of the material can be used for multifunctionalization of the sensor element using external magnetic fields during the measurements. Within this context, we investigate the room-temperature ferromagnetism in pure ZnO and Ag-doped ZnO films presenting zigzag-like columnar geometry. Specifically, we focus on the films’ structural and quasi-static magnetic properties and disclose that they evolve with the doping of low-Ag concentrations and the columnar geometry employed during the deposition. The magnetic characterization reveals ferromagnetic behavior at room temperature for all studied samples, including the pure ZnO one. By considering computational simulations, we address the origin of ferromagnetism in ZnO and Ag-doped ZnO and interpret our results in terms of the Zn vacancy dynamics, its substitution by an Ag atom in the site, and the influence of the columnar geometry on the magnetic properties of the films. Our findings bring to light an exciting way to induce/explore the room-temperature ferromagnetism of a non-ferromagnetic metal-doped semiconductor as a promising candidate for biosensor applications.This works was partially supported by the Brazilian agencies CNPq and CAPES. Furthermore, this work was also supported by the Portuguese Foundation for Science and Technology (FCT) in the framework of the Strategic Funding UID/FIS/04650/2019 and project PTDC/BTMMAT/28237/2017. A. Ferreira thanks FCT for the contract under the Stimulus of Scientific Employment (CTTI-31/18–CF (2) junior researcher contract). RMT thanks the Center for Computational Engineering & Sciences (CCES) at Unicamp for financial support through the FAPESP/CEPID Grant 2013/08293-7. LDM would also like to thank the support of the High-Performance Computing Center at UFRN (NPAD/UFRN). The work reported in this paper was supported by On-Surf Mobilizar Competencias Tecnologicas em Engenharia de Superficies, Project POCI-01-0247-FEDER-024521