Tuesday, August 14, 2012

1208.2648 (C. A. Collett et al.)

Nonlinear field-dependence and f-wave interactions in superfluid 3He    [PDF]

C. A. Collett, J. Pollanen, J. I. A. Li, W. J. Gannon, W. P. Halperin
We present results of transverse acoustics studies in superfluid 3He-B at fields up to 0.11 T. Using acoustic cavity interferometry, we observe the acoustic Faraday effect for a transverse sound wave propagating along the magnetic field, and we measure Faraday rotations of the polarization as large as 1710^{\circ}. We use these results to determine the Zeeman splitting of the Imaginary Squashing mode (ISQ) frequency, {\Omega}, an order parameter collective mode with total angular momentum J=2. We also report nonlinear field effects to the Faraday rotation, and find that theoretical predictions for the field dependence of the transverse acoustic dispersion relation, appropriate for frequencies near {\Omega}, cannot account for our data at frequencies substantially above the mode frequency. We determine the Land\'e g-factor describing the Zeeman effect for the mode, and the superfluid f-wave interaction strength, x3^-1, after extrapolation of the acoustic frequency to the mode frequency, and we show that the pairing interaction in the f-wave channel is attractive at a pressure of P=6 bar, in good agreement with previous work. We have reanalyzed earlier results for the Faraday rotation with this extrapolation procedure, and we find that the f-wave interaction is attractive at all pressures.
View original: http://arxiv.org/abs/1208.2648

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