Large two-level magnetoresistance effect in doped manganite grain boundary junctions

We performed a systematic analysis of the tunneling magnetoresistance (TMR) effect in single grain boundary junctions formed in epitaxial La(2/3)Ca(1/3)MnO(3) films deposited on SrTiO(3) bicrystals. For magnetic fields H applied parallel to the grain boundary barrier, an ideal two-level resistance switching behavior with sharp transitions is observed with a TMR effect of up to 300% at 4.2 K and still above 100% at 77 K. Varying the angle between H and the grain boundary results in differently shaped resistance vs H curves. The observed behavior is explained within a model of magnetic domain pinning at the grain boundary interface.Comment: 4 pages, 3 figures, to appear in Phys. Rev. B (Rapid Comm.

Full-scale measurement and analysis of train slipstreams and wakes. Part 2 Gust analysis

Part 1 of this paper reports results from the extensive full-scale slipstream measurements carried out as part of the AeroTRAIN project, and in particular concentrates on the ensemble analysis of this data. This paper concentrates on the analysis of maximum gusts, in order to make suggestions for modifications to the current technical specifications for interoperability (TSI) methodology. The very large data set obtained for one particular high-speed train type (the S-103) enabled the variation of slipstream gusts with vehicle speed and wind speed to be determined. It was also possible to carry out a statistical analysis of the gusts that enabled the standard uncertainty of the TSI gust parameter to be determined. It was shown that for most trains the maximum gusts occurred in the near wake of the train, but for double-unit trains the maximum gusts could occur around the gap between the units and for locomotive/coach combinations the maxima could occur around the nose of the locomotive or at the discontinuity between the train and the locomotive. Perhaps the most significant result, which could allow a considerable simplification of the TSI methodology, was that if both trackside and platform measurements for a particular train were plotted against height above the rail, then, with very few exceptions, they fell onto one curve, which implies that a trackside measurement could replace the current required platform measurement. © IMechE 2013 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav

First-passage percolation on the infinite cluster of supercritical Bernoulli percolation

Let #mu#(F) be the time constant of first-passage percolation on the square lattice with underlying distribution function F. A generalization of the definition of the travel time t from u to v is made, in order to carry over three important theorems of first-passage percolation to a generalized model that allows closed edges (with passage time t(e) = #infinity#) with some probability p > p_c, where p_c = 1/2 is the critical probability of Bernoulli percolation. (orig.)SIGLEAvailable from TIB Hannover: RO 5073(628) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman