The mysterious hourglass-shaped magnetic spectrum found in high temperature superconductors could be caused by fluctuating magnetic stripes. Credit: Oxford Univ.
Fluctuating magnetic stripes could be the cause of the
mysterious hourglass-shaped magnetic spectrum found in high temperature
superconductors, according to new research.
at Oxford Univ.. and the Institut Laue-Langevin
have used neutrons to probe the magnetic glue thought to produce high
temperature superconductivity and have identified stripes of magnetic moments
and charge as the cause of a strange hourglass-shaped magnetic spectrum. Their
findings, reported in Nature,
are a step forward in the search for a model of high temperature
research into the origins of high temperature superconductivity found in a
large class of copper oxide compounds centers on the motion of atomic magnetic
moments. Fluctuations of these moments are believed to create an attractive
force (a sort of magnetic glue) which binds electrons in pairs and allows them
to move around unimpeded giving rise to superconductivity.
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 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.
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.
cobalt oxide compound is a magnetic look-alike for the high temperature
superconductors,” said Professor Andrew Boothroyd of Oxford
Univ.’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.”