Low-field microwave absorption and magnetoresistance in iron nanostructures grown by electrodeposition on n-type lightly-doped silicon substrates

In this study we investigate magnetic properties, surface morphology and crystal structure in iron nanoclusters electrodeposited on lightly-doped (100) n-type silicon substrates. Our goal is to investigate the spin injection and detection in the Fe/Si lateral structures. The samples obtained under electric percolation were characterized by magnetoresistive and magnetic resonance measurements with cycling the sweeping applied field in order to understand the spin dynamics in the as-produced samples. The observed hysteresis in the magnetic resonance spectra, plus the presence of a broad peak in the non-saturated regime confirming the low field microwave absorption (LFMA), were correlated to the peaks and slopes found in the magnetoresistance curves. The results suggest long range spin injection and detection in low resistive silicon and the magnetic resonance technique is herein introduced as a promising tool for analysis of electric contactless magnetoresistive samples.Comment: 12 pages, 5 figure

Dinosaurs and other vertebrates from the Papo-Seco Formation (Lower Cretaceous) of southern Portugal

New vertebrate remains reported from the Papo-Seco Formation (Lower Barremian, Lower Cretaceous) of Areias do Mastro, in Cabo Espichel, SW Portugal, south of Lisbon. The marine, lagoonal, and estuarine limestones, marls, sands and gravels have yielded remains of dinosaurs and other reptiles since the 19th century. Recent paleontological prospecting produced several vertebrate remains, including turtle shell fragments, crocodilian teeth, fish and pterosaurs. Research identified both bones and teeth of fish, crocodiles, dinosaurs Baryonyx and iguanodontian, as well as a ctenochasmatoid pterosaur, and a possible ornithocheirid pterosaur. These new disclosures are an important contribution to the knowledge of vertebrate diversity from the Portuguese Cretaceous. Faunal species combination proven to be similar to other faunal associations of Barremian formations in the Iberian Peninsula.Se presentan nuevos restos fósiles de vertebrados de la formación Papo-Seco (Barremiense inferior, Cretácico Inferior), en el yacimiento de Areias do Mastro, SW de Portugal, al sur de Lisboa. En las margas, arenas, areniscas y calizas de origen marino y estuarino de esta formación localizada en el Cabo Espichel, y ya desde el siglo XIX, se han encontrado restos de dinosaurios y otros reptiles. Recientemente, nuestra prospección sacó a la luz varios restos fósiles de vertebrados, entre los que se incluyen fragmentos de caparazón de tortuga, dientes de cocodrilo, de peces actinopterigios y de pterosaurio (ctenocasmatoideo y posiblemente ornitoqueiroideo), así como algunos huesos y dientes de dinosaurios. Hemos identificado restos de Baryonyx y de ornitópodos iguanodontios. Su descubrimiento representa una importante contribución al conocimiento de la diversidad de vertebrados existentes en el Cretácico portugués. La combinación de las especies muestra ser similar a otras asociaciones de la fauna de las formaciones Barremienses en la Península Ibérica

On extra forces from large extra dimensions

The motion of a classical test particle moving on a 4-dimensional brane embedded in an $n$-dimensional bulk is studied in which the brane is allowed to fluctuate along the extra dimensions. It is shown that these fluctuations produce three different forces acting on the particle, all stemming from the effects of extra dimensions. Interpretations are then offered to describe the origin of these forces and a relationship between the 4 and $n$-dimensional mass of the particle is obtained by introducing charges associated with large extra dimensions.Comment: 9 pages, no figuer