Nonlinear field-dependence of the Imaginary Squashing Mode of superfluid ³He at moderate magnetic fields

We present the 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 of the sound up to 2070°, significantly more extensive than has been previously seen. We use these results to extend previous calculations of the Landé g factor of the imaginary squashing mode (ISQ), an order parameter collective mode with total angular momentum J = 2. We report nonlinear field splitting of the ISQ at fields as low as 0.05 T.