We report on the growth-induced properties of 30 Å thick CrPt3(111) deposits on surfaces of WSe2(0001) with a van der Waals interaction. Assemblies of (111)-oriented fcc grains are obtained with average lateral sizes ranging from 5 to 15 nm for growth temperatures increasing from 50 °C to 550 °C. The grains develop a partial L12-type chemical long-range order starting at a deposition temperature as low as 50 °C, much lower than reported for films grown on other suitable substrate surfaces. An ordering parameter of about 0.3 was found over a wide temperature range between 200 °C and 550 °C, for a deposition rate of 0.1 Å/s. Lowering the deposition rate by a factor of 5 results in a higher ordering parameter of about 0.4. Above 400 °C, ordering is accompanied by a pronounced segregation of Se atoms toward the free surface, forming a (4×4) superstructure. All samples exhibit superparamagnetic behavior with blocking temperatures that scale with the activation volume of the ferrimagnetic grains. This work shows the importance of substrate choice in reducing the ordering temperature of thin CrPt3 films, an effect that might also occur in other alloy systems.

We report on the growth of alloys ( CrPt 3 , VPt 3 , FePt) on the (0 0 0 1) surface of the layered compound WSe 2 , by co-deposition of 3d-metal and Pt atoms under ultra-high vacuum conditions. Because of weak interactions with the Se hexagonal dense planes and the strong lattice mismatch, the adatoms self-assemble and form epitaxial 3D nanostructures, which adopt lattice parameters very close to those of bulk phases. This type of growth is called quasi-van der Waals epitaxy and would allow the fabrication of nanostructured media of potential interest for magnetic recording technology. The structure and morphology of the nanostructures were studied by reflection high-energy electron diffraction, scanning tunnelling microscope and grazing incidence small angle X-ray scattering. These first results suggest that both the type of long-range chemical ordering ( L 1 2 or L 1 0 ) and the elastic properties of alloys play a role in the final morphology of nanostructures.

We report on the growth of FePt nanostructures by self-assembling on the van der Waals surface of WSe2 (0001) under ultra-high vacuum conditions. The morphology and crystalline structure of nanostructures were investigated by reflection high energy electron diffraction (RHEED), scanning tunnelling microscopy (STM) and x-ray diffraction. The FePt nanostructures grow with the (111) plane azimuthally aligned to the WSe2 (0001) plane with a narrow size distribution centred around 4.5 nm showing a rounded shape for deposition temperatures in the 300-500 degreesC range. They develop the L1(0)-type structure starting at a relatively low deposition temperature of about 200 degreesC with the occurrence of three possible variants. Moreover, segregation of Se at the growing surface was observed even in films deposited at room temperature. However, such a surfactant effect does not prevent the L1(0) ordering and could explain the perpendicular magnetic anisotropy observed in previously studied CoPt3 films grown at room temperature on WSe2. Magnetic measurements in 3 nm thick FePt(111) deposits have revealed an easy axis of magnetization in the film plane, with a coercivity strongly enhanced with L1(0) order.

CoPt3(1 1 1) films grown on WSe2(0 0 0 1) substrates consist of dense ensembles of monocrystalline nanostructures with lateral size smaller than 10 nm. For growth temperatures below 150degreesC an easy magnetization axis perpendicular to the film plane is observed with 100% remanence. Above 150degreesC the easy axis switches in the plane with the occurrence of L1(2) chemical ordering. In comparison with continuous films, the preparation of nano-structured CoPt3 films leads to a lowering of the temperature range where perpendicular magnetic anisotropy appears. (C) 2002 Elsevier Science B.V. All rights reserved.

CoPt3(111) films grown on WSe2(0001) substrates consist of dense ensembles of monocrystalline nanostructures with lateral size smaller than 10nm. For growth temperatures below 150°C an easy magnetization axis perpendicular to the film plane is observed with 100% remanence. Above 150°C the easy axis switches in the plane with the occurrence of L12 chemical ordering. In comparison with continuous films, the preparation of nano-structured CoPt3 films leads to a lowering of the temperature range where perpendicular magnetic anisotropy appears.

Epitaxial (111)-oriented CoPt3 films were deposited on WSe2(0001) substrates at room temperature using molecular beam epitaxy. We observed strong growth induced uniaxial perpendicular magnetic anisotropy which has a maximum of 3.2×106 erg/cm3 and coercivity of about 200 Oe for films with thicknesses <6 nm. At a thickness larger than 6 nm the easy magnetization axis progressively rotates into the plane of the film as the film thickness is increased. The magnetic domain structure in films with perpendicular magnetic anisotropy was investigated by photoemission electron microscopy revealing a characteristic thickness dependence near the reorientation transition.

Thin films of CoPt3(111) grown on WSe2(0001) substrates consist of dense ensembles of single-crystal nanostructures with lateral sizes smaller than 10nm. For films thinner than 6nm, an easy magnetization axis perpendicular to the film plane with 100% remanence is observed for co-deposition below 150°C, while for co-deposition at higher temperatures the easy axis switches in the plane with the occurrence of L12 chemical ordering. For thicker deposits (∼9nm), the magnetic behaviour of the continuous films is retrieved. The magnetic domain structures investigated by magnetic force microscope are also reported.

A qualitative study of the sociometric relationships was conducted among high level administrators at an urban district's central office with respect to their knowledge of and attitudes toward school-based innovations. Analysis of data found little evidence either structural or behavioral ht personnel in this school district's central office had a clear understanding of what innovation is or of the complexity inherent in implementation processes. The lack of leadership, the overreliance on externally-funded programs, and the proliferation of unrelated job responsibilities all contimbute to the district's limited effect on school-based innovations.

Specification and evaluation are significant steps in developing computer systems. In the last decade essential CAD methods and tools have been evolved supporting design automation of VLSI chips and dedicated electronic systems. Nowadays software engineering, compiler design and scheduling techniques seem to be sufficiently understood to be fit together with hardware design technologies.This paper presents a CAD methodology to specify parallel computer architectures using a stripped-off hardware description language. Based on a compact hardware specification a corresponding compiler and simulator are generated to evaluate the architecture specified. Using these architecture specific compilers and simulators the modelled hard- and software system can be evaluated indicating optimization potential.Both compilers and simulators are generated making use of a central library of CPUs, busses and memory models.