1,720,979 research outputs found
Surface and bulk analysis of Sr2FeMoO6 thin films – Sr2FeMoO6 based spin valve
Get PDFThis thesis deals with the analysis of Sr2FeMoO6 (hereafter refered to as SFMO) thin films. The material is a part of a versatile double perovskite structure family and exhibits potential attributes for basic scientific interest and for spintronic application research. The introduction begins by outlining some of the features of SFMO as a material. The basic physics relevant for this work is also discussed.
The experimental work has been mostly carried out in the Wihuri Physical Laboratory and is largely build around the fabrication and the characterization of SFMO thin films. All the SFMO thin film samples have been deposited using a pulsed laser deposition equipment. The characterization includes a surface sensitive atomic and magnetic force microscopy along with a scanning tunneling microscopy technique. The surface sensitive spectroscopy analysis for electronic structure is done using x-ray photoelectron spectroscopy. In addition, the structural characterization includes a bulk sensitive x-ray diffraction technique and magnetometry measurements.
Based on the conducted work for the structural, magnetic and electronic characterization on the SFMO films, the effects of the deposition parameters are reported. The results demonstrate the influence of substrate materials, setting a possible threshold thickness for the films to overcome the interface defects and altering the orientation of the magnetization easy axis. The atomic force microscopy method showed an improvement in thin film surface structure, as lower surface roughness, with 900 _C deposition temperature compared with higher deposition temperatures. The surface structure of the SFMO films showed evidences of a single unit cell layer growth combined with island like growth. The electronic characterization revealed that the surface contamination in the SFMO films can be cleansed with ex-situ post-annealing. The annealing leads to significant valence fluctuation without any obvious unwanted side effects on SFMO.
As a finishing touch to this work, the recent advancement in spin valve deposition is reported. The results demonstrate, to our knowledge, the first spin valve effect in SFMO thin film based devices with an organic semiconductor transport layer. The results show a notable spin valve effect at low temperature. Magnetoresistance shows a clear decay with increasing temperature, but the magnetoresistance response close to room temperature is still observed.ei tietoa saavutettavuudest
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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