PHENOMENOLOGICAL PHASE DIAGRAM OF SUPERFLUID ³ He IN A STRETCHED AEROGEL
Fomin I.A.

Received: January 21, 2014

DOI: 10.7868/S0044451014050103

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Highly anisotropic ``nematically ordered'' aerogel induces global uniaxial anisotropy in superfluid ³ He. The anisotropy lowers symmetry of ³ He in the aerogel from spherical to axial. As a result, instead of one transition temperature in a state with an orbital moment l=1 there are two, corresponding to projections l_z=0 and . This splitting has a pronounced effect on the phase diagram of superfluid ³ He and on the structures of the appearing phases. Possible phase diagrams, obtained phenomenologically on the basis of Landau expansion of the thermodynamic potential in the vicinity of the transition temperature are presented here. The order parameters corresponding to each phase and their temperature dependences are found.