1,720,997 research outputs found
Spatial distribution of superconducting properties of high rate directionally solidified YBCO samples
No full textCurrent driven transition from Abrikosov-Josephson to Josephson-like vortex in mesoscopic lateral S/S'/S superconducting weak links
Full text linkVortices are topological defects accounting for many important effects in superconductivity, superfluidity, and magnetism. Here we address the stability of a small number of such excitations driven by strong external forces. We focus on Abrikosov-Josephson vortex that appears in lateral superconducting S/S'/S weak links with suppressed superconductivity in S'. In such a system the vortex is nucleated and confined in the narrow S' region by means of a small magnetic field and moves under the effect of a force proportional to an applied electrical current with a velocity proportional to the measured voltage. Our numerical simulations show that when a slow moving Abrikosov-Josephson vortex is driven by a strong constant current it becomes unstable with respect to a faster moving excitation: the Josephon-like vortex. Such a current-driven transition explains the structured dissipative branches that we observe in the voltage-current curve of the weak link. When vortex matter is strongly confined phenomena as magnetoresistance oscillations and reentrance of superconductivity can possibly occur. We experimentally observe these phenomena in our weak links
Spatial distribution of structural and superconducting properties in high processing rate melt textured YBCO
No full text
A simple statistical phenomenological model for cation substitutions in Nd1+xBa2-xCu3O7-(delta+x/2)
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
Crystal structures, magnetic and superconducting properties of the RuSr2NdCu2Ox and RuSr2GdCu2Oy compounds
No full textWe report the magnetization and the susceptibility measurements of the RuSr2GdCu2Oy and RuSr2NdCu2Ox perovskite materials. We find that RuSr2GdCu2Oy compound exhibits a magnetic transition at Tn = 135 K followed by a superconducting one with an onset Tc = 35 K. Samples of RuSr2NdCu2Ox material have shown neither a superconductivity nor a magnetic transition. XRD measurements show that in RuSr2NdCu2Ox the Nd ions tend to be substituted by Sr ions in very high percentages. The relevance of this phenomenon on the absence of superconductivity in RuSr2NdCu2Ox is discussed. © 2002 Elsevier Science B.V. All rights reserved
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