1,720,960 research outputs found
Croissance épitaxiale et étude des propriétés structurales et magnétiques du composé antiferromagnétique Mn5Si3
No full textAntiferromagnetic (AF)materials, with their fast dynamics, robustness to external magnetic fields, and absence of stray fields, open up avenues for the development of a new generation of devices for information and communication technologies. This manuscript focuses on the epitaxial growth of thin films of Mn5Si3 by molecular beam epitaxy. This material is a model system exhibiting two distinct temperature-dependent AF orders. We have developed a codeposition technique of Si andMn on a reconstructed Si(111) (7×7) surface. A systematic study of the structural, magnetic, and magnetotransport properties was conducted as a function of the growth parameters. The growth occurs through a complex interface, composed either of an amorphous phase or aMnSi layer, with the following epitaxial relationship: Mn5Si3(0001)-[01-10]//Si(111)-[1-10]. Surface energy calculations by DFT indicate a high energy forMn5Si3, making the Si(111)-(7×7) surface unfavorable for its nucleation. An interface engineering approach involving the modification of the surface reconstruction proved to be effective in promoting the direct growth of Mn5Si3 on Si(111). Magnetic characterization by SQUID confirms the presence of a compensated magnetic order in our films. Magnetotransportmeasurements reveal a topological Hall effect, indicative of a non-coplanar spin structure below 70 K. Furthermore, a spontaneous anomalous Hall effect is observed below 240 K. This effect, absent in the bulk material, is attributed to the epitaxy-induced stabilization of a uniquemagnetic structure known as an altermagnetic structure, which macroscopically breaks time-reversal symmetry. The experimental results are in good agreement with our theoretical calculations and demonstrate that altermagnetic materials hold great promise as active elements for spintronic applications.Les matériaux antiferromagnétiques (AF), grâce à leur dynamique rapide, leur robustesse aux champs magnétiques extérieurs et l’absence de champ de fuite ouvrent des pistes pour le développement d’une nouvelle génération de dispositifs pour les technologies de l’information et de la communication. Ce manuscrit porte sur la croissance par épitaxie par jets moléculaires de films minces de Mn5Si3. C’est un matériau modèle présentant deux ordres AF distincts et dépendant de la température. Nous avons mis au point une technique de synthèse par co-dépôt de Si etMn sur une surface de Si(111) reconstruite (7×7). Une étude systématique des propriétés structurales, magnétiques et de magnétotransport a été menée en fonction des paramètres de croissance. Cette dernière s’effectue selon la relation d’épitaxieMn5Si3(0001)-[01-10]//Si(111)-[1-10] par l’intermédiaire d’une interface complexe, composée soit d’une phase amorphe, soit d’une couche de MnSi. Des calculs d’énergie de surface par DFT indiquent une énergie importante pour le Mn5Si3, rendant la surface Si(111)-(7×7) peu propice à sa nucléation. Une approche d’ingénierie d’interface consistant à modifier la reconstruction de surface s’avère efficace pour favoriser la croissance directe deMn5Si3 sur Si(111). La caractérisationmagnétique par SQUID confirme la présence d’un ordre magnétique compensé dans nos films. Le magnétotransport met en évidence un effet Hall topologique témoignant d’une structure de spin non-coplanaire au-dessous de 70 K. De plus, un effet Hall anormal spontané est observé au-dessous de 240 K. Cet effet, absent dans le matériau massif, est attribué à la stabilisation, par effet d’épitaxie, d’une structure magnétique singulière, dite altermagnétique, brisant macroscopiquement la symétrie d’inversion temporelle. Les résultats expérimentaux sont en bon accord avec nos calculs théoriques et montrent que les matériaux altermagnétiques sont très prometteurs comme éléments actifs pour des applications spintroniques
Epitaxial growth and investigation of structural and magnetic properties of the antiferromagnetic compound Mn5Si3
No full textLes matériaux antiferromagnétiques (AF), grâce à leur dynamique rapide, leur robustesse aux champs magnétiques extérieurs et l’absence de champ de fuite ouvrent des pistes pour le développement d’une nouvelle génération de dispositifs pour les technologies de l’information et de la communication. Ce manuscrit porte sur la croissance par épitaxie par jets moléculaires de films minces de Mn5Si3. C'est un matériau modèle présentant deux ordres AF distincts et dépendant de la température. Nous avons mis au point une technique de synthèse par co-dépôt de Si et Mn sur une surface de Si(111) reconstruite (7×7). Une étude systématique des propriétés structurales, magnétiques et de magnétotransport a été menée en fonction des paramètres de croissance. Cette dernière s'effectue selon la relation d’épitaxie Mn5Si3(0001)-[01-10]//Si(111)-[1-10] par l'intermédiaire d'une interface complexe, composée soit d'une phase amorphe, soit d'une couche de MnSi. Des calculs d'énergie de surface par DFT indiquent une énergie importante pour le Mn5Si3, rendant la surface Si(111)-(7×7) peu propice à sa nucléation. Une approche d’ingénierie d’interface consistant à modifier la reconstruction de surface s’avère efficace pour favoriser la croissance directe de Mn5Si3 sur Si(111). La caractérisation magnétique par SQUID confirme la présence d’un ordre magnétique compensé dans nos films. Le magnétotransport met en évidence un effet Hall topologique témoignant d’une structure de spin non-coplanaire au-dessous de 70 K. De plus, un effet Hall anormal spontané est observé au-dessous de 240 K. Cet effet, absent dans le matériau massif, est attribué à la stabilisation, par effet d’épitaxie, d’une structure magnétique singulière, dite altermagnétique, brisant macroscopiquement la symétrie d’inversion temporelle. Les résultats expérimentaux sont en bon accord avec nos calculs théoriques et montrent que les matériaux altermagnétiques sont très prometteurs comme éléments actifs pour des applications spintroniques.Antiferromagnetic (AF) materials, with their fast dynamics, robustness to external magnetic fields, and absence of stray fields, open up avenues for the development of a new generation of devices for information and communication technologies. This manuscript focuses on the epitaxial growth of thin films of Mn5Si3 by molecular beam epitaxy. This material is a model system exhibiting two distinct temperature-dependent AF orders. We have developed a co-deposition technique of Si and Mn on a reconstructed Si(111) (7×7) surface. A systematic study of the structural, magnetic, and magnetotransport properties was conducted as a function of the growth parameters. The growth occurs through a complex interface, composed either of an amorphous phase or a MnSi layer, with the following epitaxial relationship: Mn5Si3(0001)-[01-10]//Si(111)-[1-10]. Surface energy calculations by DFT indicate a high energy for Mn5Si3, making the Si(111)-(7×7) surface unfavorable for its nucleation. An interface engineering approach involving the modification of the surface reconstruction proved to be effective in promoting the direct growth of Mn5Si3 on Si(111). Magnetic characterization by SQUID confirms the presence of a compensated magnetic order in our films. Magnetotransport measurements reveal a topological Hall effect, indicative of a non-coplanar spin structure below 70 K. Furthermore, a spontaneous anomalous Hall effect is observed below 240 K. This effect, absent in the bulk material, is attributed to the epitaxy-induced stabilization of a unique magnetic structure known as an altermagnetic structure, which macroscopically breaks time-reversal symmetry. The experimental results are in good agreement with our theoretical calculations and demonstrate that altermagnetic materials hold great promise as active elements for spintronic applications
Croissance épitaxiale et étude des propriétés structurales et magnétiques du composé antiferromagnétique Mn5Si3
No full textAntiferromagnetic (AF)materials, with their fast dynamics, robustness to external magnetic fields, and absence of stray fields, open up avenues for the development of a new generation of devices for information and communication technologies. This manuscript focuses on the epitaxial growth of thin films of Mn5Si3 by molecular beam epitaxy. This material is a model system exhibiting two distinct temperature-dependent AF orders. We have developed a codeposition technique of Si andMn on a reconstructed Si(111) (7×7) surface. A systematic study of the structural, magnetic, and magnetotransport properties was conducted as a function of the growth parameters. The growth occurs through a complex interface, composed either of an amorphous phase or aMnSi layer, with the following epitaxial relationship: Mn5Si3(0001)-[01-10]//Si(111)-[1-10]. Surface energy calculations by DFT indicate a high energy forMn5Si3, making the Si(111)-(7×7) surface unfavorable for its nucleation. An interface engineering approach involving the modification of the surface reconstruction proved to be effective in promoting the direct growth of Mn5Si3 on Si(111). Magnetic characterization by SQUID confirms the presence of a compensated magnetic order in our films. Magnetotransportmeasurements reveal a topological Hall effect, indicative of a non-coplanar spin structure below 70 K. Furthermore, a spontaneous anomalous Hall effect is observed below 240 K. This effect, absent in the bulk material, is attributed to the epitaxy-induced stabilization of a uniquemagnetic structure known as an altermagnetic structure, which macroscopically breaks time-reversal symmetry. The experimental results are in good agreement with our theoretical calculations and demonstrate that altermagnetic materials hold great promise as active elements for spintronic applications.Les matériaux antiferromagnétiques (AF), grâce à leur dynamique rapide, leur robustesse aux champs magnétiques extérieurs et l’absence de champ de fuite ouvrent des pistes pour le développement d’une nouvelle génération de dispositifs pour les technologies de l’information et de la communication. Ce manuscrit porte sur la croissance par épitaxie par jets moléculaires de films minces de Mn5Si3. C’est un matériau modèle présentant deux ordres AF distincts et dépendant de la température. Nous avons mis au point une technique de synthèse par co-dépôt de Si etMn sur une surface de Si(111) reconstruite (7×7). Une étude systématique des propriétés structurales, magnétiques et de magnétotransport a été menée en fonction des paramètres de croissance. Cette dernière s’effectue selon la relation d’épitaxieMn5Si3(0001)-[01-10]//Si(111)-[1-10] par l’intermédiaire d’une interface complexe, composée soit d’une phase amorphe, soit d’une couche de MnSi. Des calculs d’énergie de surface par DFT indiquent une énergie importante pour le Mn5Si3, rendant la surface Si(111)-(7×7) peu propice à sa nucléation. Une approche d’ingénierie d’interface consistant à modifier la reconstruction de surface s’avère efficace pour favoriser la croissance directe deMn5Si3 sur Si(111). La caractérisationmagnétique par SQUID confirme la présence d’un ordre magnétique compensé dans nos films. Le magnétotransport met en évidence un effet Hall topologique témoignant d’une structure de spin non-coplanaire au-dessous de 70 K. De plus, un effet Hall anormal spontané est observé au-dessous de 240 K. Cet effet, absent dans le matériau massif, est attribué à la stabilisation, par effet d’épitaxie, d’une structure magnétique singulière, dite altermagnétique, brisant macroscopiquement la symétrie d’inversion temporelle. Les résultats expérimentaux sont en bon accord avec nos calculs théoriques et montrent que les matériaux altermagnétiques sont très prometteurs comme éléments actifs pour des applications spintroniques
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
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
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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
- …
