Zero field spin splitting in AlSb/InAs/AlSb quantum wells induced by surface proximity effects

InAs quantum well heterostructures are of considerable interest for mesoscopic device applications such as scanning probe and magnetic recording sensors, which require the channel to be close to the surface. Here we report on magnetotransport measurements of AlSb/InAs/AlSb Hall bars at a shallow depth of 20 nm. Analysis of the observed Shubnikov-de Haas oscillations and modeling show that spin splitting energies in excess of 2.3 meV occur at zero magnetic field. We conclude that the spin-splitting results from the Rashba effect due to the band bending in the quantum well. This is caused by substantial electron transfer from the surface to the quantum well and becomes significant when the quantum well is located near the surface.Comment: 14 pages, 2 figures. (To be published in APL

Spin and charge optical conductivities in spin-orbit coupled systems

We study the frequency dependent spin- and charge- conductivity tensors of a two-dimensional electron gas (2DEG) with Rashba and Dresselhaus spin-orbit interaction. We show that the angular anisotropy of the spin-splitting energy induced by the interplay between the Rashba and Dresselhaus couplings gives rise to a characteristic spectral behavior of the spin and charge response which is significantly different from that of pure Rashba or Dresselhaus case. Such new spectral structures open the possibility for control of the optical response by applying an external bias and/or by adjusting the light frequency. In addition, it is shown that the relative strength of the spin-orbit coupling parameters can be obtained through optical probing.Comment: 13 pages, 4 figures. Revised versio

Spin torque contribution to the a.c. spin Hall conductivity

Using the recently proposed definition of a conserved spin-current operator [J. Shi et al., Phys. Rev. Lett. 96, 076604 (2006)] we explore the frequency dependent spin Hall conductivity for a two-dimensional electron gas with Rashba and Dresselhaus spin-orbit interaction in response to an oscillating electric field. We show that the optical spectrum of the spin Hall conductivity exhibit remarkable changes when the new definition of spin current is applied. Such behavior is mainly due to a significant contribution of the spin torque term which is absent in the conventional form of the spin current. In addition, it is observed that the magnitude and direction of the dynamic spin Hall current strongly depends on the electric field frequency as with the interplay of the spin-orbit coupling strengths.Comment: 8 pages, 4 figures, pape

From classical to quantum spintronics: Theory of coherent spin injection and spin valve phenomena

We present a theory of coherent quantum transport in ferromagnetic/ non-magnetic/ ferromagnetic heterojunctions. We predict quantum coherence to give rise to a quantum spin valve effect that, unlike its familiar classical analog, occurs even in the absence of a net spin current through the heterostructure. Thus the relationship between spin and charge transport is qualitatively different in the presence of quantum interference than in the (semi)classical regime. This has important implications for the design of quantum coherent spintronic devices and the interpretation of experiments.Comment: 5 pages, 2 figures. To appear in EP

Preventing Soft Texture Fish Fillets through Brine Injection Technology

An exploratory study was conducted to determine if multineedle injection technology could deliver protease inhibitor ingredients into fish fillets at sufficient levels to inhibit protease activity. Pacific whiting is used as a model in this study. Fillet treatments (n=8/treatment) included noninjection (C), injection of base brine containing 3% salt and 3% sodium tripolyphosphate (B), injection of base brine and 3% egg white (BEW), and injection of base brine, 0.1% xanthan gum, and 3% dried potato extract (BPE). Xanthan gum was used as a suspension aid. Actual brine incorporation was 12.2±0.5%. Cathepsin L activity was evaluated at pH 5.5 (optimal pH) and ultimate pH. Quality measures evaluated included CIE Lab color, shear force, and lipid oxidation. Fillets injected with BEW and BPE were significantly lower in cathepsin L activity when measured at pH 5.5. BEW and BPE fillets were darker in appearance than B or C fillets. Untreated fillets (C) had higher variability in shear force value than treated fillets. There was no effect of treatment on lipid oxidation. Results suggested that injection technology can be utilized to incorporate protease inhibitor ingredients (3% EW or 3% PE) at levels sufficient to reduce cathepsin L activity in Pacific whiting fillets

FITOQUÍMICOS ANTIOXIDANTES ALIMENTARIOS COMO ESTRATEGIA DE PROMOCIÓN DE LA ESTABILIDAD OXIDATIVA DE LA CARNE DE CONEJO (Oryctolagus cuniculus L.)

One of the non-microbiological factors of greatest importance that influence the quality of meat is the oxidative process that can be generated during the manipulation of the meat or during antemortem events, such as diseases, malnutrition or transport conditions. In order to decrease these reactions andprolong the shelf life of the meat, strategies have been generated such as the addition of antioxidant phytochemicals in the diet of meat-producing animals. Rabbit meat (Oryctolagus cuniculus L.) is considered to be a functional food due to its high content of omega –3 and –6 acids, as well asfor the benefits that it has for health. This study addresses the analysis of pertinent information for the inclusion of antioxidant phytochemicals in the diet of meat-producing rabbits, and the review of research studies performed in this theme.Uno de los factores no microbiológicos de mayor importancia que influyen la calidad de la carne es el proceso oxidativo que puede ser generado durante la manipulación de la carne o durante eventos antemortem, tales como enfermedades, malnutrición o condiciones de traslado. A fin de disminuir dichas reacciones y prolongar la vida de anaquel de la carne, se han generado estrategias como la adición de fitoquímicos antioxidantes en la alimentación de animales productores de carne. La carne de conejo (Oryctolagus cuniculus L.) es considerada un alimento funcional por su alto contenido de ácidosgrasos omega 3 y 6 así como por los beneficios que aporta a la salud; el presente trabajo aborda el análisis de la información pertinente para la inclusión de fitoquímicos antioxidantes en la dieta de conejos productores de carne, así como la revisión de los trabajos de investigación realizados en el tema