In Nature this week

March 1, 2007

  1. An apology of solid state physics, if you will: Using the example of high temperature superconductivity, and the study of unusual properties of graphene, this editorial describes the intellectual richness and excitement that drives research in the area of solid state physics.
  2. Atomic force microscopy as a tool to determine the chemical identity of the atoms on a surface: AFM is a mechanical probe, which measures the force between the probe tip and the given surface. Can this force measurement be used to identify the type of atoms on the surface? This News and Views piece answers yes; one of the important components in such a determination is the realistic atomistic modelling of the experimental set-up. Unlike STM, since AFM can be used in the study of non-conducting surfaces, this will be a boon for the study of surface composition in such systems.
  3. Supercurrent flow in graphene: In another News and Views piece, Liesbeth Venema describes some surprise findings of supercurrent flow in graphene sheets; and, in these materials, in addition to conventional electron supercurrent flow, apparently, there is also a hole supercurrent flow.
  4. Some more graphene papers: An editorial on the promise of graphene; a News and Views piece on the phonon behaviour in graphenes; On the graphene rush and the progress so far; and, the breakdown of adiabatic Born-Oppenheimer approximation in graphene.
  5. Polyamorphism in metallic glasses: the News and Views piece and the paper.
  6. Phase separation in a concentrated multicomponent alloy:

    What determines the morphology of a decomposing alloy? Besides the well-established effect of the nucleation barrier, we demonstrate that, in a concentrated multicomponent Ni(Al,Cr) alloy, the details of the diffusion mechanism strongly affect the kinetic pathway of precipitation. Our argument is based on the combined use of atomic-scale observations, using three-dimensional atom-probe tomography (3D APT), lattice kinetic Monte Carlo simulations and the theory of diffusion. By an optimized choice of thermodynamic and kinetic parameters, we first reproduce the 3D APT observations, in particular the early-stage transient occurrence of coagulated precipitates. We then modify the kinetic correlations among the atomic fluxes in the simulation, without altering the thermodynamic driving force for phase separation, by changing the vacancy–solute interactions, resulting in a suppression of coagulation. Such changes can only be quantitatively accounted for with non-zero values for the off-diagonal terms of the Onsager matrix, at variance with classical models.

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