Persistent coherent spin precession in superfluid He-3-B driven by off-resonant excitation

In superfluid He-3-B under conditions of negligible normal fluid density we are able to trap a domain of coherent spin precession away from the destru ctive influence of boundaries. After the domain is generated by an NMR puls e, the free spin precession may continue for several minutes. Remarkably, w e find that these precessing domains may also be generated by cw excitation but only at a frequency considerably higher than that of the precession. W e believe that this behavior may indicate that at our temperatures the prec essing spin is able to stimulate the orbital moment into sympathetic preces sion. [S0031-9007(99)09224-8].