Abstract
We report the results of high-frequency acoustic shear impedance measurements on superfluid confined in 98% porosity silica aerogel. Using continuous wave excitation, we measured the acoustic shear impedance as a function of temperature for the sample pressures of 28.4 and . We observed the transition on warming in zero magnetic field. Our observations show that the and phases in aerogel coexist in a temperature range of about in width. We propose that differences in the relative stability of the and phases arising from anisotropic scattering can account for our observations.
- Received 27 April 2005
DOI:https://doi.org/10.1103/PhysRevB.72.094519
©2005 American Physical Society