26 October 2012
The results of a collaboration between Bristol's Stephen Hayden and colleagues based in Birmingham, Copenhagen, Hamburg, Vancouver, and Villigen were published in October by Nature Physics. The results show that high temperature superconductivity in layered cuprates can develop from an electronically ordered state called a charge density wave.
The figure shows the "checkerboard pattern" due to the modulation of the atomic positions in the CuO2 layers of YBa2Cu3O6+x caused by the charge density wave
The defining properties of superconductors are
(i) the conduction of an electric current without dissipation and
(ii) the expulsion of a magnetic field.
These properties are associated with an electronic ordering in which electrons pair and form a macroscopic quantum state. Professor Hayden and collaborators have shown that high temperature superconductivity in YBa2Cu3O6+x, can develop from another electronically ordered state called a charge density wave. In this state, electronic ordering leads to spatial modulations of the atomic positions and the charge density. The existence of such related charge ordered states may be key to understanding the origin of the high temperature superconductivity phenomenon. The experiments were performed using hard x-ray diffraction with 100keV photons at DESY in Hamburg.