Navegação Ciências Exatas e da Terra por Assunto "Física da matéria condensada"
Resultados 1-20 de 216
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Aging effects on the nucleation of Pb nanoparticles in silica
(2011) [Artigo de periódico]The ion beam synthesis of Pb nanoparticles (NPs) in silica is studied in terms of a two step thermal annealing process consisting of a low temperature long time aging treatment followed by a high temperature short time ... -
Angular dependence of energy loss in proton-helium collisions
(1994) [Artigo de periódico]The energy loss of 50 to 250 keV protons scattered under single-collision conditions from He atoms is investigated in terms of its dependence on the angle of scattering. At the higher projectile energies we observe an ... -
Angular dependence of the electronic energy loss of 800-keV He ions along the Si<100> direction
(1997) [Artigo de periódico]We present measurements of the stopping power of 800-keV 4He ions channeled along the Si(100) axis, as a function of the incidence angle. We compare the experimental results with theoretical calculations by using the ... -
Anisotropic rare-earth spin-glasses
(1982) [Artigo de periódico]We present magnetic measurements (ac and de susceptibilities and magnetization) on YEr and YGd single crystals. The longitudinal (i.e., along the c axis) susceptibility of YEr shows a typical spin-glass-like cusp, whereas ... -
An iterative, fast, linear-scaling method for computing induced charges on arbitrary dielectric boundaries
(2010) [Artigo de periódico]Simulating coarse-grained models of charged soft-condensed matter systems in presence of dielectric discontinuities between different media requires an efficient calculation of polarization effects. This is almost always ... -
Apparatus for processing of samples at high pressures and high temperatures in a fast quenching-rate regime and synthesis of polyacetylene by pulsed laser heating of confined carbon thin films
(2011) [Artigo de periódico]The pulsed laser heating of confined samples followed by ultrafast cooling constitutes an interesting route to explore the production of new phases and compounds. Indeed, in some cases the ultrafast cooling allows retaining ... -
Approximate Treatment of a Two-Dimensional Anisotropic Peierls-Hubbard Model
(1993) [Artigo de periódico]A Green-function formalism is presented to study a Peierls-Hubbard Hamiltonian in two dimensions. The 1attice consists of parallel dimerized chains with alternating nearest-neighbor hoppings t and t 11 and another hopping ... -
Barkhausen noise in the reentrant system Ni(1-X) Mn(x) : a study of the power spectra
(1993) [Artigo de periódico]In this article, the power spectra of the Barkhausen noise of Ni1-x Mnx is presented. The measurements were made in the ferromagnetic phase at several temperatures and manganese concentrations in order to map the effects ... -
Barrier-induced carrier localization effects in ordered/disordered/ordered quaternary quantum wells grown on GaAs substrates
(2006) [Artigo de periódico]Optical and micro-structural properties of ordered/disordered/ordered InGaAsP quantum wells grown on GaAs substrates were investigated by photoluminescence spectroscopy, high-resolution transmission electron microscopy and ... -
Bistability and hysteresis in the sliding friction of a dimer
(2005) [Artigo de periódico]The sliding friction of a dimer moving over a periodic substrate and subjected to an external force is studied in the steady state for arbitrary temperatures within a one-dimensional model. Nonlinear phenomena that emerge ... -
Calculation of the temperature dependence of the giant mr and application to Co/Cu multilayers
(1994) [Artigo de periódico]Most theoretical models of the giant magnetoresistance (GMR) in metallic magnetic multilayers developed up to now are for the zero-temperature limit, thus neglecting the spin-flip scattering arising from spin fluctuations ... -
Characterization of nanoparticles through medium-energy ion scattering
(2009) [Artigo de periódico]In this work we review the use of the medium-energy ion scattering (MEIS) technique to characterize nanostructures at the surface of a substrate. We discuss here how the determination of shape and size distribution of the ... -
Chemical damage in poly (phenylene sulphide) from fast ions: dependence on the primary-ion stopping power
(1996) [Artigo de periódico]Thin poly(phenylene sulphide) foils were bombarded with fast atomic ions (4He, 12C, 16O, 32S, 79Br, 127I) in the energy range between 2.5 to 78 MeV. In order to maintain the same ion track size for all impacting ions, their ... -
Co/ag multilayer film : role of annealing on the magnetic properties
(1992) [Artigo de periódico]Co( 15 A)/Ag(60 A) multilayers produced by electron beam deposition on a 50 A chromium buffer layer over a Si( 111) wafer have been studied by magnetoresistance, saturation magnetization, coercivity, and anisotropy. Annealing ... -
Co-cubstitution effects on the Fe valence in the BaFe2As2 superconducting compound : a study of hard x-ray absorption spectroscopy
(2011) [Artigo de periódico]The Fe K x-ray absorption near edge structure of BaFe₂-xCoxAs₂ superconductors was investigated. No appreciable alteration in shape or energy position of this edge was observed with Co substitution. This result provides ... -
Comment on “Exchange bias in the layered cobaltite Sr1.5Pr0.5CoO4” [J. Appl. Phys. 104, 023914 (2008)]
(2009) [Artigo de periódico]Ang et al. J. Appl. Phys. 104, 023914 2008 recently reported magnetization hysteresis loops shifted along both field and magnetization axes of layered cobaltites. The authors claimed that these shifts are characteristics ... -
Comparative study of intermetallic phases formed by direct ion implantation and radiation enhanced diffusion of tin in two kinds of steel
(1985) [Artigo de periódico]The surface layers of high-carbon and stainless steel samples, treated by both direct ion implantation of Sn + ions and radiation enhanced diffusion of tin, are analyzed by means of Rutherford backscattering and 119Sn and ... -
Comparison of computed amplitudes of magnetoresistance in spin-valve structures with wafer probe measurements
(1998) [Artigo de periódico]A code has been developed based on the semi-classical theory of giant magnetoresistance of Camley and Barnas [l]. It computes the sheet conductance and magnetoresistance of spin-valve structures. The input parameters are ... -
Compression mechanism and pressure-induced amorphization of [upsilon]-ZrW/sub 2/O/sub 8/
(2007) [Artigo de periódico]The structure of [upsilon]-ZrW2O8 has been optimized at zero pressure and also at V/V0=0.97 by means of density functional theory calculations using the B3LYP functional. As previously found for [upsilon]-ZrW2O8, tungsten ... -
Conductivity of a metal with inverse-power-law correlated impurities
(1995) [Artigo de periódico]We calculate the cooperon for a system of noninteracting electrons in the presence of random potentials with correlations W(r)= W08(r)+ W,r-<d+u> in d dimensions, for arbitrary values a and d, to first order in W1. Our ...