Evidence of the spin Seebeck effect in Ni-Zn ferrites polycrystalline slabs

We report on the observation of the spin Seebeck effect in Ni-Zn ferrites slabs with different Zn concentration. All samples have a spinel structure confirmed by XRD and TEM. We fully characterize the magnetic properties by VSM and Mössbauer spectroscopy. Samples exhibit a nonmonotonic magnetization behavior depending on the structural inversion parameter, however we found a spin Seebeck response voltage of about 25.5 nV/K independent of the magnetization and the inversion degree

Observation of huge thermal spin currents in magnetic multilayers

Thermal spin pumping constitutes a novel mechanism for generation of spin currents; however their weak intensity constitutes a major roadblock for its usefulness. We report a phenomenon that produces a huge spin current in the central region of a multilayer system, resulting in a giant spin Seebeck effect in a structure formed by repetition of ferromagnet/metal bilayers. The result is a consequence of the interconversion of magnon and electron spin currents at the multiple interfaces. This work opens the possibility to design thin film heterostructures that may boost the application of thermal spin currents in spintronics

Characteristic length scale of the magnon accumulation in Fe3O4/Pt bilayer structures by incoherent thermal excitation

The dependence of Spin Seebeck effect (SSE) with the thickness of the magnetic materials is studied by means of incoherent thermal excitation. The SSE voltage signal in Fe3O4/Pt bilayer structure increases with the magnetic material thickness up to 100 nm, approximately, showing signs of saturation for larger thickness. This dependence is well described in terms of a spin current pumped in the platinum film by the magnon accumulation in the magnetic material. The spin current is generated by a gradient of temperature in the system and detected by the Pt top contact by means of inverse spin Hall effect. Calculations in the frame of the linear response theory adjust with a high degree of accuracy the experimental data, giving a thermal length scale of the magnon accumulation (Λ) of 17 ± 3 nm at 300 K and Λ = 40 ± 10 nm at 70 K.This work was supported by the Spanish Ministry of Science (through Project No. MAT2014-51982-C2-R, including European social fund), the Aragon Regional government (Project No. E26), and Thermo-Spintronic Marie Curie CIG Project (Grant Agreement No. 304043).Peer Reviewe

Temperature dependence of the spin Seebeck effect in [Fe3O4/Pt]n multilayers

We report temperature dependent measurements of the spin Seebeck effect (SSE) in multilayers formed by repeated growth of a Fe3O4/Pt bilayer junction. The magnitude of the observed enhancement of the SSE, relative to the SSE in the single bilayer, shows a monotonic increase with decreasing the temperature. This result can be understood by an increase of the characteristic length for spin current transport in the system, in qualitative agreement with the recently observed increase in the magnon diffusion length in Fe3O4 at lower temperatures. Our result suggests that the thermoelectric performance of the SSE in multilayer structures can be further improved by careful choice of materials with suitable spin transport properties

Spin Seebeck effect in insulating epitaxial ¿-Fe2O3 thin films

We report the fabrication of high crystal quality epitaxial thin films of maghemite (¿-Fe2O3), a classic ferrimagnetic insulating iron oxide. Spin Seebeck effect (SSE) measurements in ¿-Fe2O3/Pt bilayers as a function of sample preparation conditions and temperature yield a SSE coefficient of 0.5(1) µV/K at room temperature. Dependence on temperature allows us to estimate the magnon diffusion length in maghemite to be in the range of tens of nanometers, in good agreement with that of conducting iron oxide magnetite (Fe3O4), establishing the relevance of spin currents of magnonic origin in magnetic iron oxides

Variabilidade e tendencias interanuais no fitoplancto mariño das costas de Galicia

Versión del edito

Depleción tisular de azaperona y su metabolito azaperol tras administración oral de azaperona en cerdo

Azaperone is a butyrophenone tranquilizer for swine. Food producing pigs are particularly sensitive to stress during handling and transport to the abattoir. In vivo, azaperone is partially metabolised to azaperol, a metabolite with pharmacological activity. The high and persistent concentrations of azaperone and azaperol in the injection site contra-indicates the use of azaperone using the intramuscular route for the transport of the food producing animals, pigs, to the slaughterhouse; the oral use could be an alternative to avoid residues at the injection site. The present study determined the tissue depletion of azaperone and its metabolite azaperol after oral administration of the formulation Stresnil®. Male pigs (30-45 kg of body weight) were treated with Stresnil® (single oral dose of 4 mg azaperone/kg body weight) and were sacrificed 6, 24 and 48 hours after the administration. Muscle, skin + fat, liver and kidney were collected from each animal. Azaperone and azaperol were assayed by HPLC after solid phase extraction. The concentrations of the azaperone plus azaperol in all analysed tissues did not exceed to the Maximum Residue Limit (MRL) established by the European Union (100 μg/kg in muscle, liver, kidney and skin plus fat) at any sampling time. As a consequence, from the results obtained in the present study, edible tissues of pigs treated orally with 4 mg/kg azaperone, 6 hours before to the sacrifice, might be acceptable to guarantee safety for the consumers. Nevertheless a withdrawal time of cero hours was estimated by linear regression analysis.Azaperona es un tranquilizante de tipo butirofenona usado en ganado porcino. Los cerdos son particularmente sensibles al estrés durante el manejo y transporte al matadero. La azaperona es parcialmente metabolizada in vivo a azaperol, un metabolito con actividad farmacológica. Las concentraciones altas y persistentes de azaperona y azaperol en el lugar de inyección contraindican el uso de azaperona por vía intramuscular para el transporte de cerdos de producción de carne al matadero; el uso oral podría ser una alternativa para evitar residuos en el lugar de inyección. El presente estudio determinó la depleción en los tejidos de azaperona y su metabolito azaperol después de la administración oral de la formulación Stresnil®. Cerdos machos (30-45 kg de peso corporal) fueron tratados con Stresnil® (dosis oral única de 4 mg azaperona/kg de peso corporal) y se sacrificaron 6, 24 y 48 horas después de la administración. De cada animal se obtuvo músculo, piel + grasa, hígado y riñón. Azaperona y azaperol se analizaron por HPLC tras la extracción en fase sólida. Las concentraciones de azaperona más azaperol en todos los tejidos analizados no superaron el Límite Máximo de Residuos (LMR) establecidos por la Unión Europea (100 mg / kg en el músculo, el hígado, los riñones y la piel + grasa) en ningún momento del muestreo. Como consecuencia, según los resultados obtenidos en el presente estudio, los tejidos comestibles de los cerdos tratados por vía oral con 4 mg/kg de azaperona, 6 horas antes al sacrificio, podrían ser aceptables para garantizar la seguridad de los consumidores. Sin embargo, se estimó un tiempo de espera de cero horas por análisis de regresión lineal.Facultad de Ciencias Veterinaria

The Pandora multi-algorithm approach to automated pattern recognition of cosmic-ray muon and neutrino events in the MicroBooNE detector.

The development and operation of liquid-argon time-projection chambers for neutrino physics has created a need for new approaches to pattern recognition in order to fully exploit the imaging capabilities offered by this technology. Whereas the human brain can excel at identifying features in the recorded events, it is a significant challenge to develop an automated, algorithmic solution. The Pandora Software Development Kit provides functionality to aid the design and implementation of pattern-recognition algorithms. It promotes the use of a multi-algorithm approach to pattern recognition, in which individual algorithms each address a specific task in a particular topology. Many tens of algorithms then carefully build up a picture of the event and, together, provide a robust automated pattern-recognition solution. This paper describes details of the chain of over one hundred Pandora algorithms and tools used to reconstruct cosmic-ray muon and neutrino events in the MicroBooNE detector. Metrics that assess the current pattern-recognition performance are presented for simulated MicroBooNE events, using a selection of final-state event topologies