A new NMR mode in the Landau field in superfluid3He-B

We report the experimental observation of the separate internal precession of the normal and superfluid magnetizations around the molecular Landau field in³He-B, the magnetic analog of second sound. The mode is detected by cross relaxation with conventional NMR precession when the external and Landau molecular fields have similar values. From NMR measurements down to 0.12T_c we conclude that the previously observed catastrophic relaxation phenomenon can be explained as a capture of the internal precession mode by the Larmor precession. This NMR mode provides an additional relation between the parameters F₀^a, F₂^a which taken with susceptibility data allows both parameters to be distinguished, giving for zero bar, F₀^a=–0.713 and F₂^a=0.4.