Articles in 2012

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  • The control and manipulation of the magnetization of thin metallic films by means of an electric current is a promising strategy for ensuring that potential spintronic applications are energy efficient. It is now shown that large changes in the current-induced magnetic field can arise as a result of varying the thickness of the Ta layer in Ta|CoFeB|MgO heterostructures.

    • Junyeon Kim
    • Jaivardhan Sinha
    • Hideo Ohno
  • Because it is an intrinsically slow technique, scanning tunnelling microscopy is not usually useful for studying the dynamics of particles on a surface. This issue is now solved by using scanning noise microscopy, which yields a complete characterization of copper phthalocyanine molecules on Cu(111), ranging from the dynamical processes to the underlying electronic structure at the single-molecule level.

    • Johannes Schaffert
    • Maren C. Cottin
    • Rolf Möller
    • Christian Martin
    Research Highlights
  • The evolution of microcrack damage in materials under hostile thermal and mechanical conditions has now been imaged in three dimensions by real-time in situ X-ray microtomography.

    • Philip J. Withers
    News & Views
  • Measurements of heat transport across polished nanoscale contacts formed between the tip of a scanning thermal microscope and a surface support the notion that their true contact area consists of discrete atomic contact points.

    • Yifei Mo
    • Izabela Szlufarska
    News & Views
  • The magnetocaloric effect could form the basis for efficient refrigeration technologies. The finding that large and reversible magnetocaloric effects can be induced through a strain-mediated feedback mechanism may expand the range of available magnetocaloric materials.

    • Per Nordblad
    News & Views
  • Three-dimensional ordering in liquid-crystalline polymers is induced by the photopolymerization of a mixture of mesogens sandwiched between two patterned substrates. By incorporating an infrared-sensitive dye in the mixture, polymer films that undergo reversible shape deformations on heating are formed.

    • Gustavo Fernández
    News & Views
  • President Obama's re-election was welcome news to many scientists — but it won't release the fiscal vice that's taking a grip of US research spending.

  • Excitation of organic donor–acceptor systems with high-energy light can produce hot charge-transfer states that are delocalized across the heterojunction and readily dissociate. Two studies now reveal the dynamics of this process and pave the way towards unravelling the details of the molecular landscape that favours fast photocarrier generation.

    • Carlos Silva
    News & Views
  • The spiking phenomena associated with neural activity are characterized by an impressive degree of efficiency. The fabrication of a neuristor consisting of nanoscale components represents a step towards implementing such devices in integrated circuit applications.

    • Wei Lu
    News & Views
  • Emulating the spiking phenomena associated with neural activity in technological devices offers the promise of drastically improving their efficiency and scale. The fabrication of a neuristor that consists of nanoscale Mott memristors provides a step towards making such devices practical for integrated circuit applications.

    • Matthew D. Pickett
    • Gilberto Medeiros-Ribeiro
    • R. Stanley Williams
  • Graphene has attracted considerable interest for future electronics, but the absence of a bandgap limits its direct applicability in transistors and logic devices. It is now shown that vertical integration with MoS2 and other layered materials enables the fabrication of vertical field-effect transistors with large on/off ratios and high current densities as well as complementary inverters with larger-than-unity voltage gain.

    • Woo Jong Yu
    • Zheng Li
    • Xiangfeng Duan
  • Non-trivial topological phases can allow for one-way spin-polarized transport along the interfaces of topological insulators but they are relatively uncommon in the condensed state of matter. By arranging judiciously designed metamaterials into two-dimensional superlattices, a photonic topological insulator has now been demonstrated theoretically, enabling unidirectional spin-polarized photon propagation without the application of external magnetic fields or breaking of time-reversal symmetry.

    • Alexander B. Khanikaev
    • S. Hossein Mousavi
    • Gennady Shvets
  • The standard picture of organic photovoltaics predicts that excitons, which are created under light irradiation, thermalize before dissociation into free electrons and holes. Experimental results and calculations on a low-bandgap polymer–fullerene blend now illustrate the dynamics of hot charge-transfer states and their contribution to charge generation in bulk heterojunctions.

    • G. Grancini
    • M. Maiuri
    • G. Lanzani