Spin precession waves in superfluid He3-B

Spin precession waves of homogeneously precessing domains (HPD) in superfluid He3-B have been studied at 11 bars and temperatures down to 0.45Tc. The waves were excited by an alternating longitudinal magnetic field with an axial symmetry, applied as a small perturbation ranging from 1 nT up to a few μT. When the spin precession wave is excited, two nuclear magnetic resonances simultaneously coexist: first, the high frequency resonance used for excitation of the HPD, and, second, the low-frequency resonance of the HPD wave mode. We report the first experimental evidence of the nonlinear behavior of low-frequency precession spin wave modes of the continuously maintained HPD