CMT104
Discovery of the Acoustic Faraday Effect in Superfluid 3He-B
Author(s):
Y. Lee, T. M. Haard, W. P. Halperin and J. A. Sauls
Comments:
4 pages with 3 figures
Journal:
Nature 400, 431 (1999)
[DOI]
[Press Release]
Abstract:
Acoustic waves provide a powerful tool for studying the structure of matter. The speed,
attenuation and dispersion of acoustic waves give useful details of the molecular forces
and microscopic mechanisms for absorption and scattering of acoustic energy. In solids
both compressional and shear waves occur, so-called longitudinal and transverse
sound. However, normal liquids do not support shear forces and consequently
transverse waves do not propagate in liquids with one notable exception.
In 1957 Landau predicted that the quantum liquid phase of 3He
might exhibit transverse sound at sufficiently low temperatures where the
restoring forces for shear waves are supplied by the collective action
of the particles in the fluid. Shear waves in liquid 3He involve
displacements of the fluid transverse to the direction of propagation.
The displacement defines the polarization direction of the wave similar
to electromagnetic waves. We have observed rotation of the polarization
of transverse sound waves in superfluid 3He-B in a magnetic
field. This magneto-acoustic effect is the direct analogue to the magneto-optical
effect discovered by Michael Faraday in 1845,where the polarization of
an electromagnetic wave is rotated by a magnetic field along the propagation
direction.
Paper:
[PDF]
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[arXiv]
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