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Volume 483 Issue 7389, 15 March 2012

The electronic structure of certain solids causes them to exhibit ‘Dirac points, which lie at the heart of many fascinating phenomena in condensed-matter physics. In graphene, for example, they cause electrons to act as massless Dirac fermions, able to travel at the speed of light. Two very different methods for controlling the properties of Dirac fermions are presented in this issue of Nature. In conventional solids, the electronic structure of the material cannot be varied, so it is difficult to see how the properties of Dirac fermions could be controlled. To avoid this constraint, Tarruell et al. create a tunable system of ultracold quantum gases within an adjustable honeycomb optical lattice. This model simulates condensed-matter physics, with atoms in the role of electrons. The Dirac points can be moved and merged to explore the physics of exotic materials such as topological insulators and graphene. On the cover, the band structure of artificial graphene with intersections at two Dirac points. Gomes et al. describe a more direct approach, creating an artificial form of molecular graphene by arranging carbon monoxide molecules, with atomic precision, in a honeycomb pattern on top of a two-dimensional electron system. Lattice parameters are adjustable, allowing the study of the properties of Dirac electrons and even the production of 'pseudo' electric and magnetic fields. This work highlights an innovative technique for constructing artificial materials with molecular assembly, including designer Dirac materials harbouring new ground states.Cover: Thomas Uehlinger / Inset: Shutterstock

Editorial

  • Editorial |

    Vladimir Putin's promise to increase research spending is welcome — but his country's scientific system needs a complete overhaul.

  • Editorial |

    A proposed change to Germany's constitution is needed for the future health of the universities.

  • Editorial |

    Ongoing controversy over work at Japan's Tohoku University must be resolved.

World View

  • World View |

    Plans to replicate Britain's Science Media Centre in the United States are fraught with danger, warns Colin Macilwain.

    • Colin Macilwain

Research Highlights

Seven Days

  • Seven Days |

    The week in science: Success for China’s neutrino experiment; South Africa edges ahead in race to host Square Kilometre Array; and Nobel prizewinning chemist Sherwood Rowland dies.

News

Correction

News Feature

  • News Feature |

    Since the 1960s, researchers have been scrutinizing a handful of patients who underwent a radical kind of brain surgery. The cohort has been a boon to neuroscience — but soon it will be gone.

    • David Wolman

Comment

  • Comment |

    Martin Schwab and Anita Buchli suggest ways to jump-start the stalled development of therapies for neurological diseases.

    • Martin E. Schwab
    • Anita D. Buchli
  • Comment |

    The Royal Society International Seminar Consortium describes what the next decade of mental-health drug development should look like.

    • Thomas R. Insel
    • Barbara J. Sahakian
    • John H. Williams

Books & Arts

  • Books & Arts |

    Robert Stickgold revels in a lively account of a quest to quantify consciousness.

    • Robert Stickgold
  • Books & Arts |

    Francis Halzen is exhilarated by a trek through stories of research and exploration in Antarctica.

    • Francis Halzen
  • Books & Arts |

    Computer scientist Erik Demaine uses origami to advance computational geometry and create art. His paper sculptures, made with his father, artist Martin Demaine, are now on show at the Japanese American National Museum in Los Angeles, California; from August, the exhibition will tour the United States. He explains the challenges of folding together mathematics and art.

    • Jascha Hoffman

Correspondence

News & Views

  • News & Views |

    An acid has been found to catalyse the formation of a common chemical group, the spiroacetals, and to control which mirror-image isomer of the group is made. The key to success is the acid's bulky molecular structure. See Letter p.315

    • Noah Z. Burns
    • Eric N. Jacobsen
  • News & Views |

    The drive to improve digital memory through ever-shrinking electronic circuitry will ultimately face a bottleneck. Researchers propose exploiting the room 'inside' memory elements as a solution.

    • Vincent Garcia
    • Manuel Bibes
  • News & Views |

    Genetic mutations can cause a type of heart disease called dilated cardiomyopathy, by predisposing the organ to enlarge and function poorly. It has now been found that 27% of cases are due to mutations that disrupt the muscle protein titin.

    • Elizabeth M. McNally
  • News & Views |

    The synthesis of analogues of graphene by two different means provides insight into the origins of massless particles and paves the way for studies of materials with exotic topological properties. See Letters p.302 & p.306

    • Jonathan Simon
    • Markus Greiner
  • News & Views |

    After training, animals and humans can make their thoughts interact directly with computers. A study provides evidence that the corticostriatal system of the brain is essential for this learning process.

    • David T. Blake
  • News & Views |

    The naturally occurring antibiotic lasalocid A contains a chemical structure that is not expected to form readily. The enzyme that catalyses the formation of this structure has been identified, and its activity is a revelation. See Letter p.355

    • David E. Cane
  • News & Views |

    A genome-wide, high-resolution study of DNA-binding sites for proteins that transcribe DNA into RNA reveals details about how this process occurs in vivo. See Article p.295

    • Stephen Buratowski

Article

  • Article |

    Genetic programs homologous to three vertebrate signalling centres are present in the hemichordate Saccoglossus kowalevskii and may be components of a complex, ancient genetic regulatory scaffold for deuterostome body patterning that degenerated in amphioxus and ascidians, but was retained to pattern divergent structures in hemichordates and vertebrates.

    • Ariel M. Pani
    • Erin E. Mullarkey
    • Christopher J. Lowe

Letter

Feature

  • Feature |

    Environmental concerns and more stringent laws are providing opportunities for environmental toxicologists.

    • Amanda Mascarelli

Q&A

  • Q&A |

    Following the ‘road not taken’ philosophy, stem-cell specialist earns award and start-up money.

    • Virginia Gewin

Futures

Outlook

  • Outlook |

    • Herb Brody
  • Outlook |

    Graphene is phenomenally strong, thin, flexible, transparent and conductive — and applications beckon.

    • Neil Savage
  • Outlook |

    Flecks of graphene are easy to make. But producing sheets of pristine, electronics-quality material is another matter.

    • Richard Van Noorden
  • Outlook |

    Trying to shoehorn graphene into a digital circuit isn't working. But there may be another potential path to glory.

    • Katherine Bourzac
  • Outlook |

    Transparency across the spectrum combined with electronic prowess makes graphene an ideal photonic material.

    • Neil Savage
  • Outlook |

    Nature Outlook talks to the first director of the MIT's Centre for Graphene Devices and Systems, which was created in July 2011 to foster collaboration among academic, industrial and government groups studying this form of carbon.

    • Tomás Palacios
  • Outlook |

    Exploring graphene's chemical properties reveals a world of potential away from the purely two-dimensional, says Rodney Ruoff.

    • Rodney Ruoff
  • Outlook |

    Silicon is more than an incumbent technology competing with graphene — it also has a history researchers should remember.

    • Michael Segal

Nature Outlook

  • Nature Outlook |

    Graphene

    Owing to its extraordinary electronic and optical properties, this super-strong form of carbon could radically advance technologies ranging from transistors to touch screens to solar cells to bionic implants. But first, materials scientists must figure out how to make large, pristine sheets of graphene economically.

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