Solution of the problem of catastrophic relaxation of homogeneous spin precession in superfluid 3He-B
Yu. M. Bunkov, V. S. L'vov+* 1), G. E. Volovik*∇ 1)
Centre de Recherches sur les Très Basses Températures, CNRS, BP166, 38042 Grenoble, France
+ Department of Chemical Physics, The Weizmann Institute of Science, 76100 Rehovot, Israel
*Low Temperature Laboratory, Helsinki University of Technology, P.O.Box 2200, FIN-02015, HUT, Finland
∇Landau Institute for Theoretical Physics RAS, 119334 Moscow, Russia
PACS: 67.57.Lm, 76.50.+g
Abstract
The quantitative analysis of the
"catastrophic relaxation" of the coherent spin precession in
3He-B is presented. This phenomenon has been observed below the
temperature about 0.5 Tc as an abrupt shortening of the induction
signal decay. It is explained in terms of the decay
instability of homogeneous transverse NMR mode into spin waves of the
longitudinal NMR. Recently the cross interaction
amplitude between the two modes has been calculated by Sourovtsev
and Fomin [12bun-SF] for the so-called Brinkman-Smith configuration,
i.e. for the orientation of the orbital momentum of Cooper pairs
along the magnetic field, . In their
treatment, the interaction is caused by the anisotropy of the speed
of the spin waves. We found that in the more general case of the
non-parallel orientation of L corresponding to the typical
conditions of experiment, the spin-orbital interaction provides the
additional interaction between the modes. By analyzing experimental
data we are able to distinguish which contribution is dominating in
different regimes.