1,720,958 research outputs found
Exchange-bias of NiFe/NiO bilayer
No full textExchange-bias (H-ex) of NiFe/NiO bilayers grown epitaxially on MgO(100) and MgO(111) have been measured in order to understand exchange biasing phenomena more clearly. According to HRXRD, the separate reflections of MgO and NiO were observed, which implied that NiO layers grew epitaxially on MgO substrates. The rms roughness (R-rms) of NiO on MgO(100) measured by AFM was 1.79 angstrom while that of NiO on MgO(111) was 17.85 angstrom. Despite a higher R-rms, the value of H-ex, 85 Oe in the case of NiFe/NiO on MgO(111) was larger than that of NiFc/NiO on MgO(100), 47 Oe, probably due to stronger effect of (111) texture of NiO surface. But low He,, of NiFe/NiO on MgO(111) implied that exchange biasing was generated by not only upcompensated spins but also compensated spins of NiO. He,, of NiFe/NiO bilayer grown on Si(100) was 118 Oe. According to SEM, grain size of NiO surface grown on Si(100) was very small, which mean its domain size was also very small. The explanation of the effect of domain size was consistent with random field model
A theoretical study of the effect of electronic structures of ferromagnets on giant magnetoresistance
No full textWe explain the spin-dependent electronic and physical properties of conduction electrons by using the magnitude of exchange splitting of the spin-up and the spin-down half bands in the band structure. This is done by calculating the transmission amplitudes by using a transfer-matrix method and, consequently, evaluating the ballistic spin-transport and the giant magnetoresistance (GMR) of the current perpendicular to the plane (CPP) by using the circuit theory for a ferromagnetic metal/noble metal/ferromagnetic metal simple spin valve. As a result, most transmission probabilities with transverse modes show sawtooth-like oscillations due to the strong intersubband scattering at the potential steps. Besides, the asymmetric spin-dependent potential profile induced by exchange splitting causes a stronger fluctuation in the case of spin-down transmission coefficients than it does in the case of spin-up transmission coefficients. Moreover, these oscillations disappear in the case of the spin-up transmission probabilities, but the oscillations in the spin-down case become more pronounced with exchange splitting, which, depending on exchange splitting, causes a rise in the spin-polarization and the GMR
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Variations on the Author
Get PDF“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
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe 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
Get PDFWe 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
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