Phenomenological phase diagram of superfluid 3He in a stretched aerogel

Abstract

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