1,721,055 research outputs found
Growth and characterization of charge carrier spatially confined SrMnO3/La0.7Sr0.3MnO3/SrMnO3 trilayers
No full text(SrMnO3)x/(La0.7Sr0.3MnO3)y/(SrMnO3)z (x,y,z=number of unit cells) trilayers have been grown using a Reflection High Energy Electron Diffraction calibrated layer-by-layer molecular beam epitaxy technique. X-Ray Reflectivity and X-Ray Diffraction measurements confirm the structural quality and the abruptness of the interfaces. Electrical transport property analysis as a function of temperature show effects related to the spatial confinement of the charge carriers induced by the layering. These results are important in view of future developments of oxide based heterostructures for innovative quantum devices
Enhanced transport properties in LaxMnO3−delta thin films epitaxially grown on SrTiO3 substrates: The profound impact of the oxygen content
No full textGoing 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
Magnetic imaging of pearl vortices in artificially layered (Ba 0.9Nd0.1CuO2+x)m/(CaCuO 2)n systems
Full text linkWe have used scanning SQUID magnetometry to image vortices in ultrathin (Ba0.9Nd0.1CuO2+x)(m)/(CaCuO2)(n) high temperature superconductor samples, with as few as three superconducting CuO2 planes. The Pearl lengths (Lambda=2lambda(L)(2)/d, lambda(L) the London penetration depth, d the superconducting film thickness) in these samples, as determined by fits to the vortex images, agree with those by local susceptibility measurements, and can be as long as 1 mm. The in-plane penetration depths lambda(ab) inferred from the Pearl lengths are longer than many bulk cuprates with comparable critical temperatures. We speculate on the causes of the long penetration depths, and on the possibility of exploiting the unique properties of these superconductors for basic experiments
Influence of a single disorder parameter on the conduction mechanisms in manganite thin films
No full textWe have systematically studied the transport properties of colossal magnetoresistance (CMR) manganite films at temperatures of up to 550 K by changing parameters influencing the amount of disorder in the system. Independent of the type and amount of disorder, the resistivity can always be described using a Tα-power law in the ferromagnetic-metallic phase and a thermally activated behavior in the polaronic-insulating phase. A linear correlation between both the value of the α coefficient and the polaron formation energies Eg as a function of the metal-insulator transition temperature TMI has been found. Our results indicate the possibility of describing the transport properties in CMR manganites in terms of a single disorder parameter
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
Apparent volume dependence of 1/f noise in thin film structures: Role of contacts
No full textThe experimental investigation of low-frequency noise properties in new materials is very useful for the understanding of the involved physical transport mechanisms. In this paper it is shown that, when contact noise is present, the experimental values of the normalized Hooge parameter show a fictitious linear dependence on the volume of the analyzed samples. Experimental data on noise measurements of La0.7Sr0.3MnO3 thin films are reported to demonstrate the validity of the analysis performed
Topological regime study in Bi2Se3 thin films through electric transport and low-frequency electric noise
No full textNew states of quantum matter, not directly related to conventional insulators and semiconductors, are represented by topological insulators. Due to a strong contribution of the surface to transport, these compounds have attracted an increasing interest, especially in the nanoscience field. In order to better investigate the effect of intrinsic fluctuations on the surface conduction, a detailed characterization of the low-frequency noise has been made on Bi2Se3 thin films. The experiments have been performed by varying the samples thickness and geometry, in a temperature range from 300 down to 8 K, and as a function of dc bias current and gate voltage
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