Volume 2 Issue 9, September 2006

Volume 2 Issue 9

The Klein Paradox enables a relativistic electron to pass straight through a potential barrier of at least twice its rest mass, as if the barrier were not even there. Such behaviour, which is just one of the many counterintuitive consequences of the Dirac equation, is usually expected to occur under only the most extreme of circumstances, such as in the vicinity of a black hole. But Mikhail Katsnelson and colleagues suggest that analogous conditions to those that support this paradox exist in a single sheet of graphene. They predict that when the massless Dirac fermions that carry charge in graphene encounter a square barrier at normal incidence, they too will pass through it with perfect efficiency. Moreover, analysis of related effects at oblique incidence and in bilayer graphene suggests this behaviour could be used for device applications.

Article by Katsnelson et al | News and Views by Calogeracos



  • Commentary |

    The CERN Council — representing the governments and scientists of each of the laboratory's member states — has ratified a European strategy for particle physics. Its statement is welcome, and sets out a vital programme for the future.

    • Roger Cashmore


Books and Arts

Research Highlights

News and Views

  • News & Views |

    The Klein paradox, which relates to the ability of relativistic particles to pass through extreme potential barriers, could be yet another of the strange quantum phenomena made accessible by the properties of graphene.

    • Alex Calogeracos
  • News & Views |

    Astrophysicists have proposed that sound waves could drive some of the largest explosions in the Universe. The emerging field of gravitational-wave astronomy might provide a means to listen in.

    • Teviet Creighton
  • News & Views |

    A 'real life' quantum computer requires well-protected qubits, as available in quantum optical systems, and scalability, usually the domain of solid-state devices. Polar molecules integrated with superconducting stripline resonators might offer the best of both worlds.

    • Robin Côté
  • News & Views |

    The non-superconducting state of a high-temperature superconductor is in many ways more anomalous than the superconducting state. Unlike a standard metal, the 'normal' state shows possible signs that adding or removing one electron affects all the others.

    • Dirk van der Marel
  • News & Views |

    When a tiny constriction is introduced into the path of electrons, the conductance becomes quantized. In many experiments an unexpected additional feature is observed. An explanation might now be available.

    • Klaus Ensslin
  • News & Views |

    Synchrotron X-rays from relativistic electrons confirm an important assumption of diffusive shock acceleration in the supernova remnant Cassiopeia A, but do not provide proof of the acceleration of ions to relativistic energies in supernova remnants.

    • Don Ellison
  • News & Views |

    Predicting the properties of complex organic molecules from first principles is computationally restrictive. But by modelling their behaviour as that of a series of scattering vertices, accurate calculations of their electronic structure become possible.

    • Eric R Bittner
  • News & Views |

    Scanning tunnelling microscopy studies have identified a vibrational phonon mode in a high-temperature superconductor, but is it evidence for an electron–phonon pairing interaction or is it a signature of an inelastic tunnelling channel?

    • D. J. Scalapino