Volume 6 Issue 8, August 2010

Volume 6 Issue 8

The presence of grain boundaries between misaligned crystallites is known to limit the supercurrent in a superconductor. A microscopic-based theory now reveals that charge inhomogeneities can build up at a grain boundary, blocking the superconducting current. Article p609; News & Views p559 Cover design by David Shand

Editorial

  • Editorial |

    The funding of higher education in the UK is under review, and facing a radical rethink.

Thesis

Books and Arts

Research Highlights

News and Views

  • News & Views |

    The electrical current that can be carried by a high-temperature superconductor is known to be sharply reduced by grain boundaries in the superconductor. A state-of-the-art calculation shows that this arises because of the accumulation of charge at the grain boundary.

    • James K. Freericks
  • News & Views |

    Pair formation and condensation usually occur together in Fermi superfluids. The observation of a pseudogap that implies pairing above the condensation temperature in a strongly interacting Fermi gas is thus an exciting development.

    • Mohit Randeria
  • News & Views |

    Little is known about the mechanisms that govern the injection of spins into organic molecules. A new study suggests that the metal/organic interface is key, paving the way for a new field in which interfaces are specifically designed for spin applications. This is this field of 'spinterface' science.

    • Stefano Sanvito
  • News & Views |

    Coulomb interactions can cause a rapid change in the phase of the wavefunction along a very narrow superconducting system. Such a phase slip at the quantum level is now measured in a chain of Josephson junctions.

    • David Haviland
  • News & Views |

    A superconductor that can be doped with elements that add electrons or take them away may finally lead to a clearer understanding of the transition from an insulator to a superconductor.

    • J. Orenstein
    •  & A. Vishwanath

Letters

  • Letter |

    An ultracold gas of strongly interacting fermions exhibits a pseudogap phase in which pairs of fermions exist above the superfluid transition, but lack the phase coherence of a superfluid.

    • J. P. Gaebler
    • , J. T. Stewart
    • , T. E. Drake
    • , D. S. Jin
    • , A. Perali
    • , P. Pieri
    •  & G. C. Strinati
  • Letter |

    Copper oxide superconductors do not superconduct unless electrons or holes are added to the parent compounds. A theoretical study reveals how the electrons or holes affect the host material microscopically in an asymmetric way.

    • Cédric Weber
    • , Kristjan Haule
    •  & Gabriel Kotliar
  • Letter |

    High-temperature copper oxide superconductors are usually doped with holes or electrons, not both. The discovery of a material that can be doped with both electrons and holes finally clarifies the region of low doping and the effect of the added dopants.

    • Kouji Segawa
    • , M. Kofu
    • , S-H. Lee
    • , I. Tsukada
    • , H. Hiraka
    • , M. Fujita
    • , S. Chang
    • , K. Yamada
    •  & Yoichi Ando
  • Letter |

    The gapless surface states of topological insulators could enable quantitatively different types of electronic device. A study of the topological insulating Bi2Se3 thin films finds that a gap in these states opens up in films below a certain thickness. This in turn suggests that in thicker films, gapless states exist on both upper and lower surfaces.

    • Yi Zhang
    • , Ke He
    • , Cui-Zu Chang
    • , Can-Li Song
    • , Li-Li Wang
    • , Xi Chen
    • , Jin-Feng Jia
    • , Zhong Fang
    • , Xi Dai
    • , Wen-Yu Shan
    • , Shun-Qing Shen
    • , Qian Niu
    • , Xiao-Liang Qi
    • , Shou-Cheng Zhang
    • , Xu-Cun Ma
    •  & Qi-Kun Xue
  • Letter |

    Interrupting a superconducting loop with a thin ferromagnetic film creates a so-called π-Josephson junction that shifts the phase of a current flowing in the loop by 180°. A demonstration of the use of π-junctions in a variety of device structures suggests they could enable the development of a new class of superconducting logic circuits.

    • A. K. Feofanov
    • , V. A. Oboznov
    • , V. V. Bol’ginov
    • , J. Lisenfeld
    • , S. Poletto
    • , V. V. Ryazanov
    • , A. N. Rossolenko
    • , M. Khabipov
    • , D. Balashov
    • , A. B. Zorin
    • , P. N. Dmitriev
    • , V. P. Koshelets
    •  & A. V. Ustinov
  • Letter |

    Theory predicts that the conditions generated by acoustic cavitation of a liquid could be enough to drive thermonuclear fusion. But convincing experimental evidence of this is lacking. New results now suggest that the conditions achieved are comparable to those produced in laser-driven fusion experiments.

    • David J. Flannigan
    •  & Kenneth S. Suslick

Articles

  • Article |

    In a quantum computer, the data carriers (or qubits) must be well isolated from their environment to avoid information leakage. At the same time they have to interact with one another to process information. A proposed platform based on spin qubits connected through arrays of nanoelectromechanical resonators should be able to reconcile these conflicting requirements.

    • P. Rabl
    • , S. J. Kolkowitz
    • , F. H. L. Koppens
    • , J. G. E. Harris
    • , P. Zoller
    •  & M. D. Lukin
  • Article |

    It’s long been known that the presence of grain boundaries between misaligned crystallites limits the supercurrent in a superconductor. A microscopic-based theory now reveals that charge inhomogeneities build up at a grain boundary to block the superconducting current.

    • S. Graser
    • , P. J. Hirschfeld
    • , T. Kopp
    • , R. Gutser
    • , B. M. Andersen
    •  & J. Mannhart
  • Article |

    Organic semiconductors are attractive candidates for spintronics applications because of their long spin lifetimes. But few studies have investigated how to optimize the injection of spin into these materials. A new study suggests that the metal/organic interface is key.

    • Clément Barraud
    • , Pierre Seneor
    • , Richard Mattana
    • , Stéphane Fusil
    • , Karim Bouzehouane
    • , Cyrile Deranlot
    • , Patrizio Graziosi
    • , Luis Hueso
    • , Ilaria Bergenti
    • , Valentin Dediu
    • , Frédéric Petroff
    •  & Albert Fert
  • Article |

    It is widely expected that the properties of composite fermions should be independent of those of the electrons and flux quanta from which they emerge. Measurements of anisotropic transport in AlAs quantum wells suggest this is not the case.

    • T. Gokmen
    • , Medini Padmanabhan
    •  & M. Shayegan
  • Article |

    Although the formation of beads on filaments of saliva drawn between two solid surfaces is familiar to most people, the precise mechanism responsible for such behaviour has been hotly debated. Simulations reveal that inertial effects play a pivotal role in this process.

    • Pradeep P. Bhat
    • , Santosh Appathurai
    • , Michael T. Harris
    • , Matteo Pasquali
    • , Gareth H. McKinley
    •  & Osman A. Basaran