RESUMO
Deformation of aerogel strongly modifies the orientation of the order parameter of superfluid (3)He confined in aerogel. We used a radial squeezing of aerogel to keep the orbital angular momentum of the (3)He Cooper pairs in the plane perpendicular to the magnetic field. We did not find strong evidence for a polar phase, with a nodal line along the equator of the Fermi surface, predicted to occur at large radial squeezing. Instead we observed (3)He-A with a clear experimental evidence of the destruction of the long-range order by random anisotropy-the Larkin-Imry-Ma effect. In (3)He-B we observed and identified new modes of NMR, which are impossible to obtain in bulk (3)He-B. One of these modes is characterized by a repulsive interaction between magnons, which is suitable for the magnon Bose-Einstein condensation.
RESUMO
We report on the observation of an anomalously high damping measured by a vibrating-wire resonator (VWR) immersed into superfluid at ultralow temperatures. The observed dissipation is orders of magnitude above that corresponding to friction with the dilute normal fraction and superfluid vortices. A clear pinning behavior is also observed, as well as a strong magnetic field dependence. Our analysis points to the interaction of the VWR with a planar topological defect, analogue to cosmological vacua defects, as proposed by Salomaa and Volovik.
