1,721,000 research outputs found
Bilinear exchange coupling in asymmetric Fe(110)/Cu/Fe(110) thin films studied by Brillouin Light Scattering -- Presentazione poster by R. Zivieri - Conferenza internazionale
No full textThe magnetic properties of bcc Fe(110) bilayers separated by fcc(111) Cu films of variable
thickness in the range between 0 and 33 Å have been investigated by Brillouin light scattering
(BLS). The two Fe films, 20 and 60 Å thick, are grown on the 7x7 reconstructed surface of a
Si(111) substrate using the metal-metal epitaxy on silicon technique (MMES). [1] Low energy and
Kikuchi electron diffraction analysis have revealed that the Fe films grow in the Kurdjumov-Sachs
(KS) orientation on the underlying Fe layers pseudomorphic with Cu(111).[2] The experimental
spin-wave frequency dependence on the applied magnetic field and on the incidence angle of light
is simulated using a model which includes first-order intrinsic volume and interface anisotropies.
BLS study has shown that, for Cu thickness between 0 and 33 Å, the exchange coupling is
ferromagnetic, in agreement with our surface magneto-optic Kerr effect measurements, and that the
biquadratic coupling is not negligible. The calculated BLS cross-sections agree very well with the
measured spectra.
[1] G. Gubbiotti, G. Carlotti, C. Minarini, S. Loreti, R. Gunnella, and M. De Crescenzi, Surf. Sci.
449, 218 (2000).
[2] G. Gubbiotti, L. Albini, S. Tacchi, G. Carlotti, R. Gunnella, and M. De Crescenzi, Phys. Rev. B
60, 17150 (1999). -- Presentazione poster by R. Zivieri -Conferenza internazional
Brillouin light scattering in Fe(110)/Cu/Fe(110)/Cu/Si(111) heterostructures: bilinear and biquadratic exchange magnetic couplings -- Presentazione poster by R. Zivieri - Conferenza nazionale
No full textEpitaxial Cu/Fe(20 Å)/Cu(x Å)/Fe( 60 Å) heterostructures with the Cu spacer thickness x
ranging between 0 Å and 33 Å are grown on 7x7 reconstructed surface of Si (111) substrates.
Fcc(111) Fe films grow epitaxially on a Cu(111) buffer layer up to a thickness of 6-8 Å, with
a low-spin magnetic phase, while for larger thicknesses one observes the three-dimensional
bcc Fe(110) domains in the Kurdjumov-Sachs orientation characterized by a magnetic
moment close to that of bulk Fe. [1] Brillouin light scattering (BLS) from thermally excited
spin waves has been exploited in order to study the interlayer exchange coupling between the
two Fe films. The experimental spin wave frequency dependence on both the applied
magnetic field and the incidence angle of light are simulated using a model which includes
first-order intrinsic volume and interface anisotropies and takes into account both the bilinear
and the biquadratic exchange interactions between the two ferromagnetic layers. The coupling
is found to be ferromagnetic for the whole range of Cu spacer thicknesses investigated, in
agreement with the surface magneto-optical Kerr effect (SMOKE) measurements. Using the
magnetic parameters determined by the above analysis, we have carried out a detailed
calculation of the BLS cross-section assuming the dynamic magnetization to be constant
across each magnetic film. A very good agreement between the calculated and the measured
cross sections has been obtained.
References [1] G. Gubbiotti, L. Albini, S. Tacchi, G. Carlotti, R. Gunnella, and M. De Crescenzi, Phys. Rev.
B 60, 17150 (1999). -- Presentazione poster by R. Zivieri - Conferenza nazional
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Neural blind separation for electromagnetic source localization and assessment
No full textIn this paper we present a possible approach to electromagnetic source localization using a hybrid blind separation - minimum search inversion algorithm. The total electrical field versus time emitted by the working antennas, located at different and unknown geographical positions, is used to reconstruct each separate contribute via a suitable neural network technique. When the emitted electric field and the related base frequencies have been separated for each emitting antenna, the unknown location of each emitter, is determined with a minimum-search numerical technique. The theory here presented has been applied with success to a practical problem dealing with amplitude-modulated ratio-transmissions
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Numerical Modeling for the Localization and the Assessment of Electromagnetic Field Sources
No full textNumerical modeling for the localization and the assessment of electromagnetic field sources
No full textIn this work, we present a possible approach to electromagnetic
source localization using a hybrid blind separation—
minimum search inversion algorithm. The total electrical field
versus time, emitted by the working antennas located at different
and unknown geographical positions, is used, via a suitable blind
signal processing technique based on neural networks, to reconstruct
each separate contribute. When the emitted electric signals
have been separated for each emitting antenna, the unknown
locations of the antennas are determined with a minimum-search
numerical technique
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
- …
