Spectroscopy of oscillation modes in homogeneously precessing domain of superfluid ${}^3$He-B

We study Homogeneously Precessing Domain (HPD) in superfluid ${}^3$He-B in a regular continuous-wave nuclear magnetic resonance (CW NMR) experiment. Using Fourier analysis of CW NMR time traces, we identify several oscillation modes with frequency monotonically increasing with the frequency shift of the HPD. Some of these modes are localized near the cell walls, while others are localized in bulk liquid and can be interpreted as oscillations of $\vartheta$-solitons. We also observe chaotic motion of the HPD in a certain range of temperatures and frequency shifts.