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

Determinación de Mercurio, Cadmio, Plomo y Arsénico en ríos de la zona minera de la subcuenca del Río Titihuapa, Cabañas, El Salvador, C.A.

The sub-basin of the Titihuapa River in the department of Cabañas houses part of the Tertiary volcanism of El Salvador in that region, and therefore has an abundance of minerals. The mining activity that developed since the end of the 19th century, made this area appear as one of the most favorable for the exploitation of gold and silver in El Salvador. However, this mining prosperity could have led to the metallic contamination of a good part of the Titihuapa river basin. The methodology used included taking sediment samples at sites located at the confluence points of the tributary rivers to the Titihuapa sub-basin, which were protected and transported to the laboratory for their respective analysis using atomic absorption techniques, graphite furnace method. and flame generator method. The Slight Effects Level (NEL) of the Guide for the Evaluation of Sediments, of the Department of Environmental Protection of New Jersey, 1998 was used as a parameter. The concentrations of Hg, Cd and Pb are below the values of the NEL. As concentrations, most of them exceed the NEL which is 6.0 µg / g.La subcuenca del río Titihuapa en el departamento de Cabañas alberga parte del vulcanismo Terciario de El Salvador en esa región, y por ende posee una abundancia de minerales. La actividad minera que se desarrolló desde finales del siglo XIX, hizo figurar a esta zona como una de las más propicias para la explotación de oro y plata en El Salvador. Sin embargo, esta prosperidad minera, pudo haber propiciado la contaminación metálica de buena parte de la cuenca del río Titihuapa. La metodología empleada incluyó la toma de muestras de sedimentos en sitios ubicados en los puntos de confluencia de los ríos tributarios a la subcuenca Titihuapa, las cuales fueron resguardadas y transportadas al laboratorio para su respectivo análisis mediante técnicas de absorción atómica, método de horno de grafito y método de generador de flama. Se usó como parámetro el Nivel de Efectos Leves (NEL) de la Guía Para la Evaluación de Sedimentos, del departamento de Protección Ambiental de New Jersey, 1998. Las concentraciones de Hg, Cd y Pb están por debajo de los valores de la NEL. Las concentraciones de As, la mayoría sobrepasa el NEL que es de 6.0 μg/g