Enhancing Electron Coherence via Quantum Phonon Confinement in Atomically Thin Nb3SiTe6

The extraordinary properties of two dimensional (2D) materials, such as the extremely high carrier mobility in graphene and the large direct band gaps in transition metal dichalcogenides MX2 (M = Mo or W, X = S, Se) monolayers, highlight the crucial role quantum confinement can have in producing a wide spectrum of technologically important electronic properties. Currently one of the highest priorities in the field is to search for new 2D crystalline systems with structural and electronic properties that can be exploited for device development. In this letter, we report on the unusual quantum transport properties of the 2D ternary transition metal chalcogenide - Nb3SiTe6. We show that the micaceous nature of Nb3SiTe6 allows it to be thinned down to one-unit-cell thick 2D crystals using microexfoliation technique. When the thickness of Nb3SiTe6 crystal is reduced below a few unit-cells thickness, we observed an unexpected, enhanced weak-antilocalization signature in magnetotransport. This finding provides solid evidence for the long-predicted suppression of electron-phonon interaction caused by the crossover of phonon spectrum from 3D to 2D.Comment: Accepted by Nature Physic

Cognitive style : a validation study using brain imaging and eye movements

This lecture note reviews a variety of transport and thermodynamic measurements of electron decoherence time in low-dimensional conductors at low temperature. The mechanism of dephasing by electron interaction mediated by an arbitrarily small number of magnetic impurities is neither applicable to our linear-response measurements of weak localization, nor is it observed in the recent high-field measurements of the decoherence time in nominally pure quasi-one dimensional gold wires. The source of decoherence, after extensive experiments, still appears to be intrinsic.Comment: 34 pages, 19 figures; Invited lecture at the NATO Advanced Study Institute in Geilo, Norway (2001

Effects of environmental enrichment on cognitive performance of pigs in a spatial holeboard discrimination task

This study investigated the effects of environmental enrichment on the cognitive performance of female conventional farm (growing) pigs in a spatial holeboard task. Ten pairs of littermates matched for weight were used. From each litter, one piglet was randomly assigned to a barren environment; the other was assigned to an enriched environment from 4 weeks of age. The enriched environment was double the size of the barren environment, had a floor covered with straw, a rooting area filled with peat, and one of the four different enrichment toys which were exchanged daily. Starting at 11 weeks of age, all pigs were tested in a spatial holeboard discrimination task in which 4 out of 16 holes were baited. Furthermore, basal salivary cortisol levels of all pigs were determined after the end of all testing. All pigs were able to acquire the pattern of baited holes (acquisition phase, 40 trials) and the diagonally mirrored pattern (reversal phase, 20 trials). During the acquisition phase, the reference memory performance of the enriched-housed pigs was better than that of their barren-housed littermates, i.e. they reduced visits to the unbaited set of holes. During the reversal phase, enriched-housed pigs had a better general working memory performance than the barren-housed pigs as indicated by reduced revisits to holes already visited during a trial, irrespective of whether they were of the baited or the unbaited set. The enriched-housed pigs also searched for the hidden bait faster during both phases. The environments did not affect basal salivary cortisol levels. In conclusion, environmental enrichment slightly improved the cognitive performance of pigs in a spatial learning task. We hypothesise that the long period of habituation to and testing in the holeboard acted as enrichment that partially reduced the effects of barren housing