Depth Profiling Photoelectron-Spectroscopic Study of an Organic Spin Valve with a Plasma-Modified Pentacene Spacer

[[abstract]]We report an enhanced magnetoresistance (MR) in an organic spin valve with an oxygen plasma-treated pentacene (PC) spacer. The spin valve containing PC without the treatment shows no MR effect, whereas those with moderately plasma-treated PC exhibit MR ratios up to 1.64% at room temperature. X-ray photoelectron spectroscopy with depth profiling is utilized to characterize the interfacial electronic properties of the plasma-treated PC spacer which shows the formation of a derivative oxide layer. The results suggest an alternative approach to improve the interface quality and in turn to enhance the MR performance in organic spin valves.[[incitationindex]]SCI[[booktype]]電子

Degradation of NiCr/CuNiMn/NiCr films on alumina substrates

Bruckner W, Edelmann J, Vinzelberg H, Reiss G, Knuth T. Degradation of NiCr/CuNiMn/NiCr films on alumina substrates. Thin Solid Films. 1996;280(1-2):227-232.This paper addresses the aging behaviour of NiCr/CuNiMn/NiCr triple layers on Al2O3 ceramics at temperatures up to 200 degrees C for film thicknesses d greater than or equal to 0.5 mu m. Investigations of the film structure and the increase of resistance and its temperature coefficient during the annealing process and studies of the dependence of this aging drift on both the film thickness and the storage temperature have been carried out. Furthermore, the film stress and the effect of substrate bending on resistance have been measured. The results can be explained by the irregular film structure (columns and small bridges between them), which causes stress and current concentrations as well as local creeping, cracking and oxidation processes in the micro-bridges. They are compared with such for structurally homogeneous films on silicon wafers

Untersuchungen des Verhaltens von Radioiod unter Stoerfallbedingungen in LWR in kleintechnischen Versuchsanlagen Abschlussbericht

Starting from safety considerations for WWER-type reactors main aspects of iodine chemistry are represented. By means of the use of application-oriented measuring techniques, existing equipment systems and their adaption to the requirements, investigations of the retention capacity of wet condensation systems for radioiodine were carried out. After analytical pre-tests (AAS, gaschromatography, laserspectrometry) - experiments were realized relating to both iodine absorption and iodine revolatilization. The absorption levels determined are between 92,5 and 99,9%, the iodine entrainment with revolatilization from the wet-condensation model is in the range between 0,003 and 0,0004%. (orig./HP)Ausgehend von Sicherheitsbetrachtungen fuer WWER-Reaktoren werden die Hauptaspekte der Iodchemie dargelegt. Durch Nutzung anwendungsorientierter Messtechniken, vorhandener Geraetesysteme und deren Anpassung an die Erfordernisse wurden Untersuchungen zum Rueckhaltevermoegne von Nasskondensationssystemen fuer Radioiod angestellt. Nach analytischen Vorversuchen (AAS, Gaschromatographie, Laserspektrometrie) wurden Experimente zur Iodabsorption zur Iodwiederfreisetzung durchgefuehrt. Die ermittelten Absorptionsgrade lagen zwischen 92,5 und 99,9%, der Iodaustrag bei der Wiederfreisetzung aus dem Nasskondensationsmodell bewegt sich im Bereich von 0,003 und 0,0004%. (orig./HP)SIGLEAvailable from TIB Hannover: F95B2102+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Forschung und Technologie (BMFT), Bonn (Germany)DEGerman

Towards molecular spintronics: magnetotransport and magnetism in carbon nanotube-based systems

We describe first approaches towards a carbon nanotube (CNT) based spintronics. The building blocks consist of pristine wall CNTs and metallic ferromagnetic electrodes. The devices exhibit magnetoresistive effects up to several 10% at 4.2 K origin of which is tentatively attributed to spin-dependent tunneling through an insulating barrier between the CNT and electrode. We also show results of filling multi-wall CNTs with ferromagnetic materials. These magnetic quantum wires fascinating objects in itself, revealing unusual magnetic properties. They may also be used, however, as magnetic electrodes contact to the innermost shell of the nanotube in future molecular spintronics devices. (C) 2003 Elsevier B.V. All rights reserved