904 research outputs found
Magnetic Domain Structure of La0.7Sr0.3MnO3 thin-films probed at variable temperature with Scanning Electron Microscopy with Polarization Analysis
The domain configuration of 50 nm thick La0.7SrMnO3 films has been directly
investigated using scanning electron microscopy with polarization analysis
(SEMPA), with magnetic contrast obtained without the requirement for prior
surface preparation. The large scale domain structure reflects a primarily
four-fold anisotropy, with a small uniaxial component, consistent with
magneto-optic Kerr effect measurements. We also determine the domain transition
profile and find it to be in agreement with previous estimates of the domain
wall width in this material. The temperature dependence of the image contrast
is investigated and compared to superconducting-quantum interference device
magnetometry data. A faster decrease in the SEMPA contrast is revealed, which
can be explained by the technique's extreme surface sensitivity, allowing us to
selectively probe the surface spin polarization which due to the double
exchange mechanism exhibits a distinctly different temperature dependence than
the bulk magnetization
Resonant coupling of a Bose-Einstein condensate to a micromechanical oscillator
We report experiments in which the vibrations of a micromechanical oscillator
are coupled to the motion of Bose-condensed atoms in a trap. The interaction
relies on surface forces experienced by the atoms at about one micrometer
distance from the mechanical structure. We observe resonant coupling to several
well-resolved mechanical modes of the condensate. Coupling via surface forces
does not require magnets, electrodes, or mirrors on the oscillator and could
thus be employed to couple atoms to molecular-scale oscillators such as carbon
nanotubes.Comment: 9 pages, 4 figure
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