Editor's Summary

28 August 2008

Superconductivity: altered states


One of the enduring mysteries of the high-temperature copper oxide superconductors is the existence of a 'pseudogap' — that is, an energy gap resembling the one characterizing the superconducting state but which also appears in the non-superconducting state. Kohsaka et al. have looked in detail at the electronic excitations underlying the superconducting and pseudogap states, and find two very different types of behaviour: states in momentum space that correspond to the expected delocalised electron pairs responsible for superconductivity, and some unusual states localized in real space that correspond to the pseudogap. The relationship between these two excitation types provides a new perspective on the still enigmatic relationship between the pseudogap and superconductivity, and strengthens the conceptual connection with the properties of the insulating parent compounds, where electron localization in real space is central to their behaviour.

News and ViewsCondensed-matter physics: Dual realities in superconductors

In some copper oxides, superconductivity emerges when fixed electrons become mobile. A microscopy technique reveals that this process is associated with the transfer of electrons between real and abstract spaces.

Tetsuo Hanaguri

doi:10.1038/4541062a

ArticleHow Cooper pairs vanish approaching the Mott insulator in Bi2Sr2CaCu2O8+delta

Y. Kohsaka, C. Taylor, P. Wahl, A. Schmidt, Jhinhwan Lee, K. Fujita, J. W. Alldredge, K. McElroy, Jinho Lee, H. Eisaki, S. Uchida, D.-H. Lee & J. C. Davis

doi:10.1038/nature07243