No robust phases in aerogel: 3He-A with orientational disorder in the Ginzburg-Landau model. (Comment on papers by I.A. Fomin on robust phases)
G. E. Volovik
Low Temperature Laboratory, Helsinki University of Technology, FIN-02015 HUT, Finland
L. D. Landau Institute for Theoretical Physics RAS, 117334 Moscow, Russia
PACS: 67.57.Pq
Abstract
In series of papers [12vo-Fomin,12vo-FominResponse] Fomin
introduced and discussed the so-called robust phases in a system with frozen
orientational disorder (with application to superfluid 3He in aerogel). We
show that his consideration is based on the erroneous overestimation of the
fluctuation energy which comes from the interaction of the Goldstone modes
with the frozen disorder. This interaction leads to the Imry-Ma effect, which
destroys the orientational order, but is unable to destroy the local
structure of 3He-A. There is no ground for the robust phases.