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In this paper we report on the structural and magnetic properties of GeMn layers grown on Ge(001). We show that for the optimized Mn concentration (6%) and for optimized growth temperature (close to 130 °C), GeMn samples exhibit a high Curie temperature (higher than 400 K) and Anomalous Hall Effect up to room temperature. Our GeMn layers grown at low temperature (70 °C to 130 °C) are composed of vertical Mn-rich nano-colums. Samples grown at temperatures higher than 130 °C contain GeMn nanoclusters. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

This paper presents recent results on the preparation and characterization of original magnetic nanostructures from nanoclusters preformed in the gas phase. Magnetic binary‐clusters (i.e. Co‐Sm, Co‐Pt, Co‐Ag) with rather well controlled sizes, structures and compositions, are prepared in the gas phase using a combined laser vaporization‐rare gas condensation source and subsequently deposited at low energy (LECBD : Low Energy Cluster Beam Deposition) on various functionalized substrates to grow cluster‐assembled magnetic nanostructures exhibiting specific magnetic properties. Especially a high magnetic anisotropy and consequently a high magnetic blocking temperature compatible with future applications to high density memory devices and spin electronics are expected. In this context of applications, 2D‐organized arrays of functionalized binary‐cluster assembled dots are prepared by LECBD on FIB‐functionalized substrates (FIB: Focussed Ion Beam) with the ultimate objective to reach areal densities in the range of the Tbits/in2.

Recent experimental results on the magnetic properties of an individual cobalt nanoparticle are reported in this paper. Using an improved magnetometry technique based on micro-SQUID devices coupled with an original cluster deposition technique; We have detected the magnetization reversal of a single cobalt nanocluster (3 nm in diameter, ≈ 1000 Co-atoms). The spatial distribution of the switching field has been measured at very low temperature leading to the determination of the magnetization reversal process and the magnetic anisotropy axes and constants characteristic of such nanoparticles. These results are compared to those obtained from macroscopic measurements on cluster assemblies using the Vibrating Sample Magnetometry and X-ray Magnetic Circular Dichroı̈sm techniques. Magnetic measurements are complemented with structural studies of the cluster core and surface to understand the origin of magnetic anisotropy in Co-nanoclusters.

Paleomagnetic measurements have been conducted on the Mio-Pliocene series along the external sedimentary Hellenic arc, in order to detect the presence or absence of rotational deformations in different sections of the arc.

A corer has been designed to sample and recover deep marine sediments without loss of hydrostatic pressure. The device consists of: the piston corer device of classical design; a pressure-retaining core module (1.5 m long) with two high-pressure (60-80MPa) self-cleaning spherical valves at either end for pressure sealing the sample; and an acoustic control system for monitoring the performance of the corer during operation and commanding the closure of the valves. The core barrel is modular so that the pressure section can be placed in any position along the 6-m core string. Sediment sampled in adjacent sections depressurizes, thus allowing a direct comparison between this and the sediment maintained under pressure. During sediment penetration, the corer control unit, housed in the tail section, detects the passage of the piston past two ultrasonic detectors activating the closure of the two spherical valves. Field tests of the control unit have verified its ability to perform successfully when subjected to the dynamic forces of a coring operation. Recovered sediment samples will be available for laboratory investigations; high pressure apparatus is already available for studying the migration of radionuclides and heavy metals in marine sediments. The interface needed between the corer and this equipment is under development.

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This review presents the recent progress in computational materials design, experimental realization, and control methods of spinodal nanodecomposition under three- and two-dimensional crystal-growth conditions in spintronic materials, such as magnetically doped semiconductors. The computational description of nanodecomposition, performed by combining first-principles calculations with kinetic Monte Carlo simulations, is discussed together with extensive electron microscopy, synchrotron radiation, scanning probe, and ion beam methods that have been employed to visualize binodal and spinodal nanodecomposition (chemical phase separation) as well as nanoprecipitation (crystallographic phase separation) in a range of semiconductor compounds with a concentration of transition metal (TM) impurities beyond the solubility limit. The role of growth conditions, codoping by shallow impurities, kinetic barriers, and surface reactions in controlling the aggregation of magnetic cations is highlighted. According to theoretical simulations and experimental results the TM-rich regions appear in the form of either nanodots (the dairiseki phase) or nanocolumns (the konbu phase) buried in the host semiconductor. Particular attention is paid to Mn-doped group III arsenides and antimonides, TM-doped group III nitrides, Mn- and Fe-doped Ge, and Cr-doped group II chalcogenides, in which ferromagnetic features persisting up to above room temperature correlate with the presence of nanodecomposition and account for the application-relevant magneto-optical and magnetotransport properties of these compounds. Finally, it is pointed out that spinodal nanodecomposition can be viewed as a new class of bottom-up approach to nanofabrication. [ABSTRACT FROM AUTHOR]