Monday, March 21, 2011

Stripes 'play key role' in superconductivity

Stripes 'play key role' in superconductivity: Recent debate has focused on the cause of an unusual hourglass shape found in the spectrum of these magnetic fluctuations. The origin of this pattern, which is found in many if not all high temperature superconductors, is thought to relate to an alternating pattern of spin and charge stripes found within the atomic layers but so far it has been hard to prove a link between the two phenomena.
The researchers instead turned their attention to an insulating cobalt oxide with a similar magnetic stripe pattern. Using neutron scattering at the ILL the scientists measured the atomic-scale fluctuations in its magnetism and uncovered the same hourglass pattern in the data. Their results provide strong evidence that magnetic stripes are the cause of the hourglass spectrum and play an important role in high temperature superconductivity.
‘Our cobalt oxide compound is a magnetic look-alike for the high temperature superconductors,’ said Professor Andrew Boothroyd of Oxford University’s Department of Physics, who led the work at Oxford. ‘Its lack of mobile electrons prevents it from becoming superconductive, allowing us to use neutron scattering to look in detail at nano-scale fluctuations in the magnetic motion without the complicating effects of superconductivity. The experiment allows us to isolate the source of the much-debated hour-glass spectrum.’

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