Event-triggered design for discrete-time nonlinear systems with control constraints

Nonlinear Dynamics - In order to solve the constrained-input problem and reduce the computing resources, a novel event-triggered optimal control method is proposed for a class of discrete-time...     

Ni thin films vacuum-evaporated on polyethylene naphthalate substrates with and without the application of magnetic field

We study the structural properties of the surface roughness, the surface mound size and the interfacial structure in Ni thin films vacuum-deposited on polyethylene naphthalate (PEN) organic substrates with and without the application of magnetic field and discuss its feasibility of fabricating quantum cross (QC) devices. For Ni/PEN evaporated without the magnetic field, the surface roughness decreases from 1.3 nm to 0.69 nm and the surface mound size increases from 32 nm to 80 nm with the thickness increased to 41 nm. In contrast, for Ni/PEN evaporated in the magnetic field of 360 Oe, the surface roughness tends to slightly decrease from 1.3 nm to 1.1 nm and the surface mound size shows the almost constant value of 28-30 nm with the thickness increased to 35 nm. It can be also confirmed for each sample that there is no diffusion of Ni into the PEN layer, resulting in clear Ni/PEN interface and smooth Ni surface. Therefore, these experimental results indicate that Ni/PEN films can be expected as metal/insulator hybrid materials in QC devices, leading to novel high-density memory devices.     

Influence of thermal annealing on oxidation states of Al-oxide in spin tunneling junctions

The dielectric constant in annealing coercive differential spin tunneling junctions Co/Al-oxide/Co has been investigated in order to clear the influence of thermal annealing on oxidation states. Al oxidized naturally in pure O₂ shows the relative dielectric constant of 10–40 before annealing. It indicates that Al oxidized in pure O₂ can be AlO₂ because the dielectric constant of AlO₂ is approximately 22.7. This dielectric measurement result is in good agreement with XPS analysis results that O/Al ratio is 1.9–2.0. After annealing at temperature ranging from room temperature up to 250 °C, the relative dielectric constant approaches approximately 8.0, which is equal to that of Al₂O₃. This indicates that the phase of Al-oxide is changing from AlO₂ to Al₂O₃ by annealing. This dielectric measurement will help investigate the oxidation state, such as chemical composition for junctions themselves.     

Crystallographic report: Bis(tripyridyldiamine)zinc(II) tetrabromozincate(II) hydrate

The zinc(II) atom in the complex cation of [Zn(tpda)₂][ZnBr₄]·H₂O is octahedrally coordinated, whereas the zinc(II) atom in the anion is tetrahedrally coordinated. The cations and the anions are connected by hydrogen bonds, affording a two‐dimensional network. Copyright © 2005 John Wiley & Sons, Ltd.     

Crystallographic report: Chlorobis(tripyridyldiamine)cadmium(II) nitrate

The Cd(II) atom in [(tpda)₂CdCl]NO₃, is octahedrally coordinated to one chlorine and five pyridyl‐nitrogen atoms. The coordination cations and nitrate anions are connected by multiple hydrogen bonds, affording a two‐dimensional structure. Copyright © 2005 John Wiley & Sons, Ltd.     

Aluminum thickness dependence of resistance change in spin tunneling junctions Co/Al-oxide/Co

The oxidation states of Al-oxide layer and the leakage current density in coercive differential spin tunneling junctions Co/Al-oxide/Co have been investigated in order to clear the mechanism of the increasing resistance change. X-ray photoelectron spectroscopy analysis shows that the resistance change increases with decreasing unoxidized Al, which can be qualitatively explained by using first-principle band calculation based on linear-muffin-tin-orbital atomic-sphere-approximation method. The resistance change decreases with increasing leakage current density, which originates from Schottky effect. Reduction of unoxidized Al and leakage current density originating from Schottky effect is required to obtain the large resistance change in spin tunneling junctions.