Persistent signal; Coherent NMR state trapped by orbital texture

The so called persistent NMR signal, that was found in superfluid He-3-B at very low temperature corresponds to new states of coherent spin precession. They are distinct from the previously known homogeneously precessing domain (HPD), whose stability is supported by the specific profile of the spin-orbital potential. The new states are stabilized by the orbital texture which provides the required feedback mechanism supporting the precession with a single frequency. New precessing states are obtained by pumping the energy into the spin wave modes localized in the potential well formed by the orbital texture. When the intensity of a given spin wave increases, it influences the Orbital degrees of freedom. As a result the potential well is modified and hence modifies the eigen-frequency of the spin-wave mode, which in turn affects the orbital texture. The frequency of this self-consistent precessing state thus depends on the longitudinal magnetization, omega(S-z). If d omega(S-z)/dS(z) < 0 this coherent mode spontaneously arises in pulsed NMR and persists with a continuous drift of the frequency. This state of magnetic superfluidity is similar to the Bose condensate formed the ground state of the potential well, in the case when the well self-consistently depends on the population of the condensate.