Transport Properties and Electronic Specific Heat of La2−x Ba x Cu1−y Zn y O4+d Bulk

The effect of the partial substitution of Cu by Zn and La by Ba in La: 214 prepared by conventional solid state reaction method has been investigated by using Hall coefficient, Seebeck coefficient and electronic specific heat measurements, over the wide temperature range between 4.2 K and 300 K, in magnetic fields up to 5 T. The samples with y=0 and d=0, showed superconductivity for x between 0.055 and 0.30. The critical temperature, the Hall and Seebeck coefficients strongly depend on Zn content. The phonon specific heat C _ph and electronic specific heat C _el have been extracted from the total specific heat C. Zn-doping effect on the (T)=C _el/T behavior suggests that the large range stripe order and the fluctuating stripe suppress the singlet formation and pseudo gap.     

Classical Mechanical Analogies in Wide Dirty SFS Junctions

The Usadel equation in a bulk superconductor and a ferromagnet is noticed to be mathematically similar to the equation of motion of a pendulum. A solution technique developed to solve the classic pendulum is applied to analytically determine the order parameter of the singlet state in a superconductor-ferromagnet-superconductor (SFS) trilayer with a constant, uniform exchange field.     

Electron tomography and 3D molecular simulations of platinum nanocrystals

This work reports on the morphology of individual platinum nanocrystals with sizes of about 5 nm. By using the electron tomography technique that gives 3D spatial selectivity, access to quantitative information in the real space was obtained. The morphology of individual nanoparticles was characterized using HAADF-STEM tomography and it was shown to be close to a truncated octahedron. Using molecular dynamics simulations, this geometrical shape was found to be the one minimizing the nanocrystal energy. Starting from the tomographic reconstruction, 3D crystallographic representations of the studied Pt nanocrystals were obtained at the nanometer scale, allowing the quantification of the relative amount of the crystallographic facets present on the particle surface.     

Preparation and functional characterization of magnetoelectric Ba(Ti1-xFex)O3-x/2 ceramics. Application for a miniaturized resonator antenna

Diluted magnetic oxides attracted a great interest in the last years as materials for spintronics and magnetoelectric devices. We propose in the present paper such a magnetoelectric ceramic system for an application as miniaturized resonator antenna in GHz range. BaTi_1-xFe_xO_3-x/2 (0?≤?x?≤?0.02) polycrystalline ceramics have been produced by solid state reaction. X-ray diffraction analysis and Rietveld refinement have shown that Fe doping of BaTiO₃ lattice produces a transition from tetragonal crystalline symmetry (for x?≤?0.01) to a superposition of tetragonal and hexagonal phases for the compositions x?=?0.015 and 0.02. As result of Fe addition, the Curie temperature of BaTi_1-xFe_xO_3-x/2 ceramics exhibit a shift from 127?°C towards lower values and reaches 85?°C for x?=?0.02. A competition between weak ferromagnetic and antiferromagnetic character as a function of composition and temperature is determined both by the presence of transition metal ion and of the oxygen vacancies. Due to its electromagnetic properties, an optimized composition x?=?0.01 was used for producing a miniaturized antenna which was found to show a frequency dependent S₁₁ response similar to the simulated one.     

Synthesis and characterization of hydrogels containing biodegradable polymers

BACKGROUND: Amphiphilic block and graft copolymers constitute a very interesting class of polymers with potential for biomedical applications, due to their special characteristics, which derive from the combination of properties of hydrophilic and hydrophobic moieties. In this work, the synthesis and biodegradation of poly(2‐hydroxyethyl methacrylate)‐graft‐poly(L ‐lactide) are studied. RESULTS: The graft copolymers were synthesized using the macromonomer technique. In a first step, methacryloyl‐terminated poly(L ‐lactide) macromonomers were synthesized in a wide molecular weight range using different catalysts. Subsequently, these macromonomers were copolymerized with 2‐hydroxyethyl methacrylate in order to obtain a graft copolymer. These new materials resemble hydrogel scaffolds with a biodegradable component. The biodegradation was studied in hydrolytic and enzymatic environments. The influence of different parameters (molecular weight, crystallinity, ratio between hydrophilic and hydrophobic components) on the degradation rate was investigated. CONCLUSION: Based on this study it will be possible to tailor the release properties of biodegradable materials. In addition, the materials will show good biocompatibility due to the hydrophilic poly(2‐hydroxyethyl methacrylate) hydrogel scaffold. This kind of material has potential for many applications, like controlled drug‐delivery systems or biodegradable implants. Copyright © 2008 Society of Chemical Industry     

DeltaE effect for polycrystalline ferromagnetic rods.

We performed experimental and computational studies of the acoustic transfer power coefficient for carbon steel cylindric bars placed in axial magnetic field. By experiment, the transmission coefficients of velocity were measured for ferromagnetic bars during the first magnetization curve below saturation. Using the magnetic and magnetostriction material measurements we obtained the profile of the magnetostriction along the distance for a ferromagnetic cylindrical rod placed in a magnetic field parallel with its axis. The data were compared with numerical results obtained by computer simulation, under the assumption of spatial dependent acoustic impedance and phase velocity, leading to the conclusion that the Young modulus is affected by the magnetoelastic interaction according to a linear decrease.     

Review of terahertz technology development at INO

Journal of Infrared, Millimeter, and Terahertz Waves - Over the past decade, INO has leveraged its expertise in the development of uncooled microbolometer detectors for infrared imaging to produce...     

Anisotropic Magneto‐Coulomb Properties of 2D–0D Heterostructure Single Electron Device

Fabrication and spintronics properties of 2D–0D heterostructures are reported. Devices based on graphene (“Gr”)–aluminium nanoclusters heterostructures show robust and reproducible single‐electron transport features, in addition to spin‐dependent functionality when using a top magnetic electrode. The magnetic orientation of this single ferromagnetic electrode enables the modulation of the environmental charge experienced by the aluminium nanoclusters. This anisotropic magneto‐Coulomb effect, originating from spin–orbit coupling within the ferromagnetic electrode, provides tunable spin valve‐like magnetoresistance signatures without the requirement of spin coherent charge tunneling. These results extend the capability of Gr to act both as electrode and as a platform for the growth of 2D–0D mixed‐dimensional van der Waals heterostructures, providing magnetic functionalities in the Coulomb blockade regime on scalable spintronic devices. These heterostructures pave the way towards novel device architectures at the crossroads of 2D material physics and spin electronics.     

Numerical Simulation of Low-Frequency Noise in Polysilicon Thin-Film Transistors

Numerical simulations of low-frequency noise are carried out in two technologies of N-channel polysilicon thin-film transistors (TFTs) biased from weak to strong inversion and operating in the linear mode. Noise is simulated by generation/recombination processes. The contribution of grain boundaries on the noise level is higher in the strong inversion region. The microscopic noise parameter that is deduced from numerical simulations is lower than the macroscopic one defined according to the Hooge empirical relationship and deduced from noise measurements. The higher macroscopic value is attributed to the drain-current crowding induced by nonconducting spots in the devices due to structural defects. The ratio of these two noise parameters can be considered as an indicator to qualify TFT technology.