Strong Orientational Effect of Stretched Aerogel on the 3He Order Parameter

Johannes Elbs (1) , Yuriy M. Bunkov (1) , Eddy Collin (1) , Henri Godfrin (1) , Grigory E. Volovik (2)

1 NEEL - UBT - Ultra-basses températures
2 Aalto - Aalto university low temperature physics

Deformation of aerogel strongly modifies the orientation of the order parameter of superfluid 3He confined in aerogel. We used a radial squeezing of aerogel to keep the orbital angular momentum of the 3He 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 3He-A with a clear experimental evidence of the destruction of the longrange order by random anisotropy--the Larkin-Imry-Ma effect. In 3He-B we observed and identified new modes of NMR, which are impossible to obtain in bulk 3He-B. One of these modes is characterized by a repulsive interaction between magnons, which is suitable for the magnon Bose-Einstein condensation.

Mots clés: superfluids; BEC; spin supercurrent; superfluid 3He

Domaines: Gaz Quantiques [cond-mat.quant-gas]

Johannes Elbs, Yuriy M. Bunkov, Eddy Collin, Henri Godfrin, Grigory E. Volovik. Strong Orientational Effect of Stretched Aerogel on the 3He Order Parameter. Physical Review Letters, 2008, 100 (21), pp.215304. ⟨10.1103/PhysRevLett.100.215304⟩. ⟨hal-00920419⟩