We calculate electronic transport properties of multilayered granular alloys, composed of discontinuous Co layers embedded in Ag alternated with complete Ag layers. We focus our attention on the conductivity dependance on the shape and size of the clusters. The electronic structure is self-consistently calculated using a tight binding hamiltonian which includes a Hubbard term within the unrestricted Hartree–Fock approximation. We obtain different transport regimes depending on the growth conditions and transport direction. 相似文献
The magnetic extension of the Thomas-Fermi-Weizs?cker kinetic energy is used within density-functional-theory to numerically
obtain the ground state densities and energies of two-dimensional quantum dots. The results are thoroughly compared with the
microscopic Kohn-Sham ones in order to assess the validity of the semiclassical method. Circular as well as deformed systems
are considered.
Received 26 October 2000 and Received in final form 14 December 2000 相似文献
The structures of the carbon sublayers in the annealed Co/C soft X-ray multilayers fabricated by using a dual-facing-target
sputtering system have been characterized by transmission electron microscopy (TEM) and Raman spectroscopy (RS). The results
suggest that the structural variations in the carbon layers can be roughly divided into three stages, i.e. ordering, crystalline
and grain growth stages. At the ordering stage with annealing temperatures below 400°C, the amorphous carbon layers change
from ones of bond-angle disorder and fourfold-bonding only to ones of threefold-bonding. At the crystalline stage, the amorphous
carbon layers in the as-deposited multilayers crystallize to graphite crystallites in the annealing temperature range of 500–600°C.
At the grain growth stage, the specimens are annealed at temperatures higher than 700°C. A growth in the graphite crystallite
dimensions is observed, which is consistent with the TEM results.
Project supported by the National Natural Science Foundation of China and Beijing Zhongguancun Associated Center of Analysis
and Measurement. 相似文献
Thin Co/Fe multilayers were e-beam evaporated in ultra-high vacuum, keeping constant the Co layer thickness and varying that
of Fe in the 0.5÷15 nm range. By increasing the Fe layer thickness, a component of magnetization perpendicular to the film
plane rises up, and long and parallel magnetic domains (stripe domains) appear. The phenomenon is explained on the basis of
the competition between the magnetoelastic anisotropy induced by stresses at the interfaces, and the shape anisotropy constraining
the magnetization in the film plane.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
In this paper, we report on the tunable metal‐enhanced fluorescence (MEF) of Ag nanostructures. Because of the good MEF properties of the highly dendritic Ag nanostructures, we obtained an increase of up to 25 times for the weak fluorescence of porphyrin molecules (Por4–). More importantly, by the introduction of a stimulus‐responsive PAA/PDDA multilayer film as an interlayer, the distance between the fluorophores and the Ag nanostructures could be tuned by immersing the substrates into solutions of different ionic strength or pH. The MEF behavior of the composite films could thus be tuned in a controlled manner, because of the distance dependent nature of the MEF effects.
Interfacial magnetic anisotropy in a Pt/Co1-xFex /Pt multilayer is tuned by doping iron atoms into the cobalt layer.The perpendicular magnetic anisotropy and out-of-plane coercivity are found to decrease with increasing x.For a specific x,the out-of-plane coercivity acquires a maximal value as a function of the thickness of the CoFe layer.At low temperature,the coercivity is enhanced.Small coercivity but reasonably large perpendicular magnetic anisotropy can be obtained by controlling the x and CoFe layer thickness. 相似文献