Optical properties of exfoliated MoS2 coaxial nanotubes - analogues of graphene

We report on the first exfoliation of MoS2 coaxial nanotubes. The single-layer flakes, as the result of exfoliation, represent the transition metal dichalcogenides' analogue of graphene. They show a very low degree of restacking in comparison with exfoliation of MoS2 plate-like crystals. MoS2 monolayers were investigated by means of electron and atomic force microscopies, showing their structure, and ultraviolet-visible spectrometry, revealing quantum confinement as the consequence of the nanoscale size in the z-direction

Mn magnetism in icosahedral quasicrystalline Al72.4Pd20.5Mn7.1

The unusual magnetism of manganese atoms in an icosahedral Al72.4Pd20.5Mn7.1 single-grain quasicrystal was studied by Al-27 nuclear magnetic resonance (NMR), magnetic susceptibility, and electrical resistivity measurements. Between room temperature and 50 K both the Al-27 NMR linewidth and the frequency shift exhibit a Curie-Weiss-type, 1/(T-theta) temperature dependence. At lower temperatures a significant narrowing of the linewidth, concomitant with a reduction of the frequency shift is observed. These features can be explained by a gradual reduction of the local exchange magnetic field at the position of the Al-27 nuclei that is transferred from the manganese d moments via the conduction electrons. Two possible origins of this phenomenon are discussed: (i) the Kondo-like screening of manganese moments by the conduction electrons and (ii) the ''resistivity'' -damping of the RKKY interaction due to increasing electron localization at low temperatures

Controlling Luttinger liquid physics in weakly coupled spin ladders under magnetic field

International audienceLuttinger liquid (LL) physics is a remarkable manifestation of strong correlations in one-dimensional (1D) systems. Physical properties of a LL are determined by two Luttinger parameters characterizing the power law decay of most observables. In addition to the difficulty in realising LLs, no precise control over Luttinger parameters is usually possible. Notable exception are gapless phases of 1D antiferromagnets (AFs), such as spin chains and ladders, where the Luttinger parameters can be directly tuned by an external magnetic field. Here we demonstrate that CuBr4(C5H12N)2 (BPCB), a material containing weakly coupled spin-1/2 Heisenberg AF ladders, is a unique system for controlling and probing the LL physics. Using 14N nuclear magnetic resonance we quantitatively characterize the variation of Luttinger parameters over the gapless phase of BPCB. This allows us to fully account for the phase transition to a 3D ordered phase at temperatures below 110 mK, which takes place due to weak inter-ladder exchange coupling, in terms of weakly coupled LLs

Reply to "Comment on 'Extrinsic origin of the insulating behavior of polygrain icosahedral Al-Pd-Re quasicrystals' "

We clarify issues raised in the preceding Comment regarding the viewpoint that the highly porous and oxidized arc-melted polygrain i-Al-Pd-Re samples could reveal intrinsic electrical transport properties of this icosahedral family. Flux-grown single-grain i-Al-Pd-Re samples of superior structural quality do not show insulatinglike behavior, and their transport properties are on common ground with all other Al-based icosahedral families.This article is published as Dolinšek, J., P. J. McGuiness, M. Klanjšek, I. Smiljanić, A. Smontara, E. S. Zijlstra, S. K. Bose, I. R. Fisher, M. J. Kramer, and P. C. Canfield. "Reply to “Comment on ‘Extrinsic origin of the insulating behavior of polygrain icosahedral Al-Pd-Re quasicrystals’”." Physical Review B 76, no. 21 (2007): 216202. DOI: 10.1103/PhysRevB.76.216202. Copyright 2007 American Physical Society. Posted with permission

Surface changes on crystalline stones due to salt crystallisation

International audienc

Processes Linking Parents’ and Adolescents’ Religiousness and Adolescent Substance Use: Monitoring and Self-Control

Empirical evidence suggests that religiousness is related negatively to adolescent substance use; yet, we know little about how such protective effects might occur. The current study examined whether parents’ and adolescents’ religiousness are associated positively with parental, religious, and self-monitoring, which in turn are related to higher self-control, thereby related to lower adolescent substance use. Participants were 220 adolescents (45% female) who were interviewed at ages 10–16 and again 2.4 years later. Structural equation modeling analyses suggested that higher adolescents’ religiousness at Time 1 was related to lower substance use at Time 2 indirectly through religious monitoring, self-monitoring, and self-control. Higher parents’ religiousness at Time 1 was associated with higher parental monitoring at Time 2, which in turn was related to lower adolescent substance use at Time 2 directly and indirectly through higher adolescent self-control. The results illustrate that adolescents with high awareness of being monitored by God are likely to show high self-control abilities and, consequently, low substance use. The findings further suggest that adolescents’ religiousness as well as their religious environments (e.g., familial context) can facilitate desirable developmental outcomes