Magnetic resonance and spin waves in theAphase of superfluidHe3

Abstract

Extending an idea due to Leggett, that the longitudinal resonance in the $A$ phase of superfluid ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ is considered as an internal Josephson effect, we discuss the nuclear magnetic resonance as well as spin waves in the $A$ phase of superfluid ${}_{}{}^3{}_{}{}^{}\mathrm{He}$. The spin-wave dispersion in the hydrodynamic regime is determined explicitly.